[CMake] CMAKE_C_COMPILER for MSVC doesn't have a path

[Brandon Van Every]

When I examine CMAKE_C_COMPILER for other compilers, such as MinGW, I
get a full path.  So I can execute it with EXECUTE_PROCESS and extract
the compiler version number fairly readily.  For MSVC though, all I
get is "cl".  CMake knows where that cl actually is, but it's not
telling me.  There's no guarantee that cl.exe is in my path, so
EXECUTE_PROCESS commands just fail.

Is there some technical reason why only "cl" is returned, or did
nobody previously care?


Cheers,
Brandon Van Every