[CMake] Running a command after generation of Makefile

[Johny]

Hey,

I was trying to use the SYSTEM option in the include_directories command 
, however it does not seem to work on the MACOSX platform. So i wrote a 
little fix which basically replaces all the -I${foldername} with 
-isystem ${foldername}. However these commands need to be executed after 
my makefiles are generated and i wud like to not have the user execute 
another cmake script before running make. Is it possible?

Cheers,
Johny