Now users can use a different compiler from GCC like Clang by for example
doing `CC=clang make`.
Change-Id: I664a36df79f7496a56d89bdb61948b2eda33a6b4
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/3082
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>