CMakeBuildConfig: Clean up unnecessary and/or duplicate MSVC compiler and linker flags. Some references on the subject: http://msdn.microsoft.com/en-us/library/59a3b321.aspx, http://msdn.microsoft.com/en-us/library/bxwfs976.aspx, http://blogs.msdn.com/b/branbray/archive/2005/07/08/437078.aspx