[CMake] getting consistent symbol exporting across platforms

[Christopher Harvey]

Hi,
I read that gcc exports all symbols by default where as with msvc one 
has to put something like dllExport in the symbols to be exported. I'd 
like to have the same symbols be exported on both msvc and gcc. Is there 
a way I could use cmake to make both compilers behave the same way while 
creating a shared library?

thanks,
Chris.