Patch merged into coreboot/master: Update crossgcc Makefile for new buildgcc arguments

the following patch was just integrated into master:
commit 403ba7726a0235c7399fec75baa769ca4eacc018
Author: Martin Roth 
Date:   Sat Jun 27 19:09:05 2015 -0600

Update crossgcc Makefile for new buildgcc arguments

The script `util/crossgcc/buildgcc` was rewritten in commit 85b07d68
    (buildgcc: move to a package centric user interface) and the switches
    changed.  This patch does the following:

- IASL was split out of the gcc builds, so needs a target of its own.
    - Add clang build target
    - Update the build-ARCH targets as buildgcc -G no longer builds gcc.
    - Rework all the targets to use common targets to call buildgcc
    - Split the tempfile clean from the regular clean
    - Change the 'all' target to leave the tempfiles until all architectures
    are built so that if one fails and needs a rebuild, it doesn't have to
    start from scratch.
    - Add an all_without_gdb target
    - Add clang build to all

Change-Id: I4ff720eab6d9b72d00757fd2b632e6d9a6c25aa3
    Signed-off-by: Martin Roth 
    Reviewed-on: http://review.coreboot.org/10679
    Tested-by: build bot (Jenkins)
    Reviewed-by: Stefan Reinauer

See http://review.coreboot.org/10679 for details.

-gerrit