[CMake] MSVC71 WholeProgramOptimization flag (/LTCG) fixed?

[Simon Sasburg]

My findings, with visual studio 2008 express, are that you don't
really need to have WholeProgramOptimization=TRUE to fix this warning.
It suffices to add /LTCG to the link options of all executables and modules.

Unfortunately I'm not able to get cmake to add the /LTCG flag to the
module link flags.
See also here: http://www.cmake.org/pipermail/cmake/2008-October/024446.html

Also, it seems weird that this flag is reported not to work in VS8+,
as both VS8 Express, and VS9 Express show the whole program
optimization options in the IDE.