[coreboot-gerrit] Patch merged into coreboot/master: 34de29a build system: move more clang handling to xcompile

the following patch was just integrated into master:
commit 34de29aeb3a8d5013044fea9387609ea63d8ecf6
Author: Patrick Georgi 
Date:   Thu Jun 4 13:45:40 2015 +0200

build system: move more clang handling to xcompile

clang requires some additional options to disable warnings which
    can be handled by xcompile.
    Also drop the hard coded clang compilers in Makefile

Change-Id: I0f12f755420f315127e6d9adc00b1246c6e7131b
    Signed-off-by: Patrick Georgi 
    Reviewed-on: http://review.coreboot.org/7612
    Tested-by: build bot (Jenkins)
    Reviewed-by: Stefan Reinauer

See http://review.coreboot.org/7612 for details.

-gerrit