When we check for a working compiler we print a message of the form:
Check for working <LANG> compiler: ...
At one time CMAKE_<LANG>_COMPILER was not well-defined for all
generators so we printed the generator name instead of the path to
the compiler. Nowadays we always know the compiler, so update the
message to print it unconditionally. This is more informative than
the generator name, especially when a toolset (cmake -T) is used.
Suggested-by: Gregor Jasny <gjasny@googlemail.com>