VS: Place per-source preprocessor definitions after target-wide ones

When the VS 2010+ generators were first implemented in commit 7491f529
(ENH: first pass at VS 10, can bootstrap CMake, but many tests still
fail, 2009-06-25, v2.8.0~546), the per-source preprocessor definitions
were placed before target-wide preprocessor definitions for consistency
with the behavior of VS 9 2008 and below.  However, those generators
are not used much anymore.  Instead prefer consistency with the order
used by the Ninja and Makefile generators.

Help/release/dev/compile-options-order.rst

+compile-options-order
+---------------------
+
+* The :ref:`Visual Studio Generators` for VS 2010 and above now place
+  per-source preprocessor definitions after target-wide preprocssor
+  definitions.  This makes VS consistent with the :ref:`Ninja Generators`
+  and the :ref:`Makefile Generators`.

Source/cmVisualStudioGeneratorOptions.cxx

@@ -418,7 +418,9 @@ void cmVisualStudioGeneratorOptions::OutputPreprocessorDefinitions(
   }
 
   std::ostringstream oss;
-  const char* sep = "";
+  if (this->Version >= cmGlobalVisualStudioGenerator::VS10) {
+    oss << "%(" << tag << ")";
+  }
   std::vector<std::string>::const_iterator de =
     cmRemoveDuplicates(this->Defines);
   for (std::string const& di : cmMakeRange(this->Defines.cbegin(), de)) {
@@ -437,11 +439,7 @@ void cmVisualStudioGeneratorOptions::OutputPreprocessorDefinitions(
       }
     }
     // Store the flag in the project file.
-    oss << sep << define;
-    sep = ";";
-  }
-  if (this->Version >= cmGlobalVisualStudioGenerator::VS10) {
-    oss << ";%(" << tag << ")";
+    oss << ';' << define;
   }
 
   this->OutputFlag(fout, indent, tag, oss.str());