VC) TUNDRA_NO_BOOST: enforce inclusion of (${OGRE_DIR}/include/OGRE/RenderSystems/Direct3D9
HighPerfClock.h: use Win.h to include Windows headers.
Use SetupCompileFlagsWithPCH() instead of SetupCompileFlags() as OpenAssetImport provides StableHeaders. Include Win.h in OpenAssetImport's StableHeaders.h in order to prevent compilation error (Win.h(13) : fatal error C1189: #error :  Error: Trying to include winsock2.h after windows.h! This is not allowed! See this file for fix instructions.) due to suspected Windows header inclusions lurking in from assimp's headers.