Building with gcc?

[Matthew Fleming]

I'm trying to test a change to gcc, and I'd like to do a full
buildworld/buildkernel using the gcc compiler.  So I added this to my
/etc/src.conf (and make.conf, since I can't remember under which scenarios
they're different):

WITHOUT_CLANG=YES
WITH_GCC=YES
WITH_GNUCXX=YES

and I started a buildworld.  It's currently building clang.

Why is it building clang?

Thanks,
matthew