COMP: Optimize visual studio service pack check

In commit r22096, the CMake module "CMakeDetermineVSServicePack" was used.
In addition to invoke some extra "try_compile" statement increasing
the configure time, it was failing complaining dll mspdb80.dll or
mdpdb100.dll were missing.

This commit fixes the problem by directly using "CMAKE_CXX_COMPILER_VERSION"

Thanks to Brad Lowekamp for his help elaborating this set of patches.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22098 3bd1e089-480b-0410-8dfb-8563597acbee