[CMake] how can I filter compiler warnings?

[Kevin Burge]

I need to be able to filter warnings out of the compilation output from 
specific files:

"/usr/include/pthread.h", line 990.27: 1506-450 (I) Obsolete 
non-prototype-style function declaration.
"/usr/include/pthread.h", line 1049.42: 1506-450 (I) Obsolete 
non-prototype-style function declaration.
"/usr/include/pthread.h", line 1050.42: 1506-450 (I) Obsolete 
non-prototype-style function declaration

On our old build system, we replaced cc with a ruby script that filtered 
the output.  I never did figure out the way to do this with cmake.  I'd 
rather have cmake filter it if it can.

Please let me know if there's a way to do this.

Thank you,
Kevin Burge