[Cmake] build flags

[Cross, Geoff (CRD)]

> CMAKE_CXX_FLAGS_RELEASE = /MD /O2
> CMAKE_CXX_FLAGS_MINSIZEREL = /MD /O1
> CMAKE_CXX_FLAGS_DEBUG = /MDd /Zi /Od /GZ
> CMAKE_CXX_FLAGS = /W3 /Zm1000 /FD /GX /GR

I'm getting defaults of:

CMAKE_CXX_FLAGS_DEBUG = /MDd /Zi /Od /Gz /O2

which is illegal:

Command line error D2016 : '/O2' and '/GZ' command-line options are incompatible