Merge topic 'VS10-PrecompiledHeader-default'

f0ae381 VS: Disable precompiled headers unless enabled by project (#12930)

Source/cmVisualStudio10TargetGenerator.cxx

@@ -1205,6 +1205,7 @@ bool cmVisualStudio10TargetGenerator::ComputeClOptions(
   // Get preprocessor definitions for this directory.
   std::string defineFlags = this->Target->GetMakefile()->GetDefineFlags();
   clOptions.FixExceptionHandlingDefault();
+  clOptions.AddFlag("PrecompiledHeader", "NotUsing");
   clOptions.Parse(flags.c_str());
   clOptions.Parse(defineFlags.c_str());
   clOptions.AddDefines