Define wxNO_RTTI if RTTI support is disabled for g++ or MSVC.

Define wxNO_RTTI if RTTI support is disabled for g++ or MSVC.

For g++ it could have been possible to define wxNO_RTTI in configure itself
but it seems better/simpler/more maintainable to do it in C++ code. As for
MSVC, we already define wxNO_RTTI correctly if build/msw/makefile.vc is used
but not if (modified or rebaked) project files are used and detecting RTTI
support in the code is the only way to fix it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62698 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775