libpayload: don't overwrite CFLAGS

Makefile already sets it to contain the architecture specific flags,
don't drop them, but add to that instead.

Change-Id: I147e6480ab2b3c1ee4f4ace511197b4ba94280b8
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10804
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed