For every instance of '.if ${CC} == "foo"' or '.if ${CC} != "foo"' in
Makefiles or *.mk files, use ${CC:T:Mfoo} instead, so only the basename
of the compiler command (excluding any arguments) is considered.

This allows you to use, for example, CC="/nondefault/path/clang -xxx",
and still have the various tests in bsd.*.mk identify your compiler as
clang correctly.

ICC if cases were also changed.

Submitted by: Dimitry Andric <dimitry at andric.com>