[wxMac] Building with CMake

[John Ralls]

I'm trying to build the swWxGuiTesting library, which uses CMake, and  
I'm trying to do it on OS-X.
CMake insists on changing the include flags to g++ for the wx include  
directories from '−I' to '−isystem'. This chokes g++, making it  
think that global scope prototypes should be C instead of C++ (making  
overloading not work, for example).

I've tried a few things to change CMake's mind, none successful. Does  
anyone here know the trick?

Regards,
John Ralls