lang/icon: Port does not respect "USE_GCC=4.6+ override and stops building duet to "BROKEN" flag

If someone overrides the default system compiler which is in my case
CLANG 3.2 (on  FreeBSD 10.0-CURRENT #1 r240885M: Mon Sep 24 12:30:44
CEST 2012 amd64), the if-statement does always take place and prevents
lang/icon to be build:

[...]
.if ${CC} == "clang" || ${CXX} == "clang++"
BROKEN=                does not pass all tests when compiled with clang
.endif
[...]

In /etc/makefile.conf, I include an additional file located in
/usr/local/etc/ports.conf which contains statements like

# lang/icon
.if ${.CURDIR:M*/lang/icon}
USE_GCC=                4.6+
#CC=                    cc
#CXX=                   c++
#CPP=                   cpp
.endif

I'd expect the build system system to have already setup CC, CPP and CXX
according to the specifications made in /etc/make.conf and the
overridings in my ports.conf file with "USE_GCC=4.6+", but obviously
this doesn't happen.

I expect by setting "USE_GCC=4.6" all the nasty stuff like -Wl,rpatch=,
CC,CXX,CPP et cetera is set for me and I do not have to take care of it.

How can this problem be solved?

I think this will become an issue when CLANG will be the default compiler.

oh