Visual Studio generators need toolset-specific flag maps
In VS 2010 and above we support the CMAKE_GENERATOR_TOOLSET option to set the
<PlatformToolset> element in generated
.vcxproj files. However, we currently always use a flag map associated with the version of Visual Studio matching the generator in use (e.g.
cmVS14CLFlagTable.h) instead of matching the specific toolset in use as MSBuild expects.