winbase.h: Removed CreateMutexExA declaration that uses LPCTSTR instead of LPCSTR and conflicts with synchapi.h.

git-svn-id: svn://svn.code.sf.net/p/mingw-w64/code/trunk@6050 4407c894-4637-0410-b4f5-ada5f102cad1
Introduce option --rt for enabling RT's IDL language-extensions.


git-svn-id: svn://svn.code.sf.net/p/mingw-w64/code/trunk@6051 4407c894-4637-0410-b4f5-ada5f102cad1