[CMake] How to identify MSVC-compatible compiler?

[Dave Abrahams]

Is there a variable that will tell me when the compiler supports
MSVC-compatible command-line flags?  I'd like to have something cleaner
than checking for 

  WINDOWS AND ( MSVC OR INTEL )

If not, I can of course roll my own, but this seems like something that
should be in CMake's "standard library."

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com