Help: Document explicitly that policy OLD behavior is deprecated

The most likely documentation page a project author will read in
response to a policy warning is the page for the policy itself.
Add to every policy documentation page a note explicitly stating
that the OLD behavior is deprecated.  Also mention this in the
cmake_policy() command documentation that explains how to set a
policy to OLD.
Suggested-by: Fraser Hutchison <fraser.hutchison@gmail.com>

Help/command/cmake_policy.rst

@@ -53,6 +53,8 @@ policy warning by setting the policy state to ``OLD``.  Alternatively
 one may fix the project to work with the new behavior and set the
 policy state to ``NEW``.
 
+.. include:: ../policy/DEPRECATED.txt
+
 Checking Policy Settings
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

Help/manual/cmake-policies.7.rst

@@ -20,11 +20,11 @@ for a policy, also avoiding the warning.  Each policy can also be set to
 either ``NEW`` or ``OLD`` behavior explicitly on the command line with the
 :variable:`CMAKE_POLICY_DEFAULT_CMP<NNNN>` variable.
 
-Note that policies are not reliable feature toggles.  A policy should
-almost never be set to ``OLD``, except to silence warnings in an otherwise
-frozen or stable codebase, or temporarily as part of a larger migration
-path. The ``OLD`` behavior of each policy is undesirable and will be
-replaced with an error condition in a future release.
+A policy is a deprecation mechanism and not a reliable feature toggle.
+A policy should almost never be set to ``OLD``, except to silence warnings
+in an otherwise frozen or stable codebase, or temporarily as part of a
+larger migration path. The ``OLD`` behavior of each policy is undesirable
+and will be replaced with an error condition in a future release.
 
 The :command:`cmake_minimum_required` command does more than report an
 error if a too-old version of CMake is used to build a project.  It

Help/policy/CMP0000.rst

@@ -28,3 +28,5 @@ a warning.  An included file may set CMP0000 explicitly to affect how
 this policy is enforced for the main CMakeLists.txt file.
 
 This policy was introduced in CMake version 2.6.0.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0001.rst

@@ -17,3 +17,5 @@ below.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0002.rst

@@ -24,3 +24,5 @@ property ALLOW_DUPLICATE_CUSTOM_TARGETS with a Makefiles generator).
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0003.rst

@@ -100,3 +100,5 @@ when setting the policy once will probably fix all targets.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0004.rst

@@ -21,3 +21,5 @@ target is created by an add_executable or add_library command.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0005.rst

@@ -22,3 +22,5 @@ limitations of the escaping implementation.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0006.rst

@@ -20,3 +20,5 @@ without a BUNDLE DESTINATION.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0007.rst

@@ -13,3 +13,5 @@ empty elements in a list.
 This policy was introduced in CMake version 2.6.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0008.rst

@@ -30,3 +30,5 @@ pass it directly to the native build tool unchanged.
 This policy was introduced in CMake version 2.6.1.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0009.rst

@@ -17,3 +17,5 @@ as an additional argument to the FILE command.
 This policy was introduced in CMake version 2.6.2.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0010.rst

@@ -16,3 +16,5 @@ and is treated as always being ``NEW``.
 This policy was introduced in CMake version 2.6.3.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0011.rst

@@ -20,3 +20,5 @@ cmake_policy PUSH and POP.
 This policy was introduced in CMake version 2.6.3.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0012.rst

@@ -23,3 +23,5 @@ dereferencing variables with such names.
 This policy was introduced in CMake version 2.8.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0013.rst

@@ -17,3 +17,5 @@ with an error.
 This policy was introduced in CMake version 2.8.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0014.rst

@@ -13,3 +13,5 @@ behavior for this policy is to report an error.
 This policy was introduced in CMake version 2.8.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0015.rst

@@ -15,3 +15,5 @@ paths by appending the relative path to CMAKE_CURRENT_SOURCE_DIR.
 This policy was introduced in CMake version 2.8.1.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0016.rst

@@ -11,3 +11,5 @@ in this case.
 This policy was introduced in CMake version 2.8.3.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt

Help/policy/CMP0017.rst

@@ -17,3 +17,5 @@ from the CMake modules directory.
 This policy was introduced in CMake version 2.8.4.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
 the cmake_policy command to set it to OLD or NEW explicitly.
+
+.. include:: DEPRECATED.txt