Android: Add placeholders for platform-specific compiler settings

Add infrastructure modules to be loaded for Clang and GNU compilers
when targeting Android platforms.

Modules/Platform/Android-Clang-C.cmake

+include(Platform/Android-Clang)
+__android_compiler_clang(C)

Modules/Platform/Android-Clang-CXX.cmake

+include(Platform/Android-Clang)
+__android_compiler_clang(CXX)

Modules/Platform/Android-Clang.cmake

+#=============================================================================
+# Copyright 2015-2016 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+# This module is shared by multiple languages; use include blocker.
+if(__ANDROID_COMPILER_CLANG)
+  return()
+endif()
+set(__ANDROID_COMPILER_CLANG 1)
+
+include(Platform/Android-Common)
+
+macro(__android_compiler_clang lang)
+  __android_compiler_common(${lang})
+endmacro()

Modules/Platform/Android-Common.cmake

+#=============================================================================
+# Copyright 2015-2016 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+# This module is shared by multiple languages; use include blocker.
+if(__ANDROID_COMPILER_COMMON)
+  return()
+endif()
+set(__ANDROID_COMPILER_COMMON 1)
+
+macro(__android_compiler_common lang)
+endmacro()

Modules/Platform/Android-GNU-C.cmake

+include(Platform/Android-GNU)
+__android_compiler_gnu(C)

Modules/Platform/Android-GNU-CXX.cmake

+include(Platform/Android-GNU)
+__android_compiler_gnu(CXX)

Modules/Platform/Android-GNU.cmake

+#=============================================================================
+# Copyright 2015-2016 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+# This module is shared by multiple languages; use include blocker.
+if(__ANDROID_COMPILER_GNU)
+  return()
+endif()
+set(__ANDROID_COMPILER_GNU 1)
+
+include(Platform/Android-Common)
+
+macro(__android_compiler_gnu lang)
+  __android_compiler_common(${lang})
+endmacro()