[CMake] Globally add compiler options for gcc

[Stephen Collyer]

This is almost certainly a FAQ but I can't find
an answer anywhere: I'm building using gcc under
Linux and VS2005 under Win32. I want to add, say,
-Wall globally to everything compiled under Linux
but leave the compile options for Win32 untouched.

How do I do that ?

-- 
Regards

Steve Collyer
Netspinner Ltd