[CMake] MSVC71 WholeProgramOptimization flags (/LTCG and /GL)

[Hicham Mouline]

Hello,
Re http://www.itk.org/Bug/view.php?id=6794
What I basically want to do is to set /LTCG for the linker flags anytime the
build type is release, with msvc9.

I understand the compiler (in msvc8:vs2005 and msvc9:vs2008) deprecated
/LTCG. Only linker now takes that.

I've tried setting in the CMakeFile  
SET(LINK_FLAGS "${LINK_FLAGS} /LTCG")

But it doesn't get set when I open the solution with vs2008.

I've tried setting it in CMAKE_CXX_FLAGS, but same problem.

Regards,
Hicham