[coreboot-gerrit] Patch merged into coreboot/master: 23b4e4c Makefile.inc: Only add `-Wno-unused-but-set-variable` for GCC

the following patch was just integrated into master:
commit 23b4e4c4e80c0acd17c088c6bdde8c3bfccce898
Author: Paul Menzel 
Date:   Wed Apr 8 10:53:39 2015 +0200

Makefile.inc: Only add `-Wno-unused-but-set-variable` for GCC

Clang (3.5) does not know that option.

error: unknown warning option '-Wno-unused-but-set-variable'; did you mean '-Wno-unused-const-variable'? [-Werror,-Wunknown-warning-option]

Fix up commit f69a99db (coreboot: x86: enable gc-sections) to only add
    that option, when GCC is used.

Change-Id: I65b41133a806df1803ccc445e27184c579a718a0
    Signed-off-by: Paul Menzel 
    Reviewed-on: http://review.coreboot.org/9377
    Tested-by: build bot (Jenkins)
    Reviewed-by: Aaron Durbin

See http://review.coreboot.org/9377 for details.

-gerrit