How to handle WITH_CLANG_IS_CC in ports

[Tobias Rehbein]

Hi all,

I am the maintainer of ganes/stonesoup. This port builds fine with gcc.
It also builds with clang, if the MAKE_ARGS are tweaked.

Currently I can check for

	${CC:T:M*clang*}

to know if I have to change the MAKE_ARGS for building with clang or
not.

In CURRENT cc is clang and the environment variable CC is no longer set.
This lets the build of games/stonesoup fail. My question is how to
correctly check if cc is clang or not. My first guess was something
along the lines of

	${CC:T:M*clang*} || (defined(WITH_CLANG_IS_CC) && ${CC:T:Mcc})

but I guess there is some kind of official way to handle this (ideally
warpped in some Mk macro.

Regards

	Tobias