options for forcing use of GCC

I need to hold off using CLANG for a while at $JOB. We are moving to a 
newer FBSD in the vicinity of 10.0 but we need to keep the gcc in hte 
picture for a bit longer before switching.  What options do I put into 
various /etc/make.conf to keep CLANG out ofhte picture until we are 
ready for it?

 From reading various posts I see:
WITHOUT_CLANG="yes"
CC=gcc
CXX=g++
CPP=gcc -E
but that doesn't seem complete to me.

For now I want to not compile clang in our official build environment.
(and obviously not use it until we are ready for it later this year.)

What other hooks do I need to set?

Julian