Patch merged into coreboot/master: toolchain.inc: Improve help messages for coreboot toolchain

the following patch was just integrated into master:
commit 335a9b61b3856486645727dfdef8ed32b036c860
Author: Martin Roth 
Date:   Wed Nov 25 12:44:15 2015 -0700

toolchain.inc: Improve help messages for coreboot toolchain

Show better help text on how to compile the coreboot toolchain or use
    an unsupported toolchain.

Change-Id: I64a2159d324d673784669b2464c1a2769b048678
    Signed-off-by: Martin Roth 
    Reviewed-on: https://review.coreboot.org/12557
    Tested-by: build bot (Jenkins)
    Reviewed-by: Patrick Georgi

See https://review.coreboot.org/12557 for details.

-gerrit