Patch merged into coreboot/master: 2c342f5 Makefile.inc: Detect if a working clang binary exists before set

the following patch was just integrated into master:
commit 2c342f508065db05f31ac04a9dee934759d7c039
Author: Edward O'Callaghan 
Date:   Fri Jun 27 18:22:53 2014 +1000

Makefile.inc: Detect if a working clang binary exists before set

Let us not assume the 'clang' binary exists and is working just because
    the user selected it in .config

Change-Id: Iad3cbf4a7cda0e1c4d435fbe426b7247233973ea
    Signed-off-by: Edward O'Callaghan 
    Reviewed-on: http://review.coreboot.org/6141
    Tested-by: build bot (Jenkins)
    Reviewed-by: Idwer Vollering

See http://review.coreboot.org/6141 for details.

-gerrit