Create a variable "GCC", which defaults to the content of CC, but allows
the user to provide a gcc to use in this instance, even when normally a
different tool is chosen. That helps with scan-build (see next patch),
and might help with distcc, ccache etc, too.
Signed-off-by: Patrick Georgi <firstname.lastname@example.org>
Acked-by: Stefan Reinauer <email@example.com>