buildgcc: Clarify required user action

When required tools are missing, try to give the user more detailed
information on how to solve the problem.

Change-Id: Ifa21c1af38a036a7d4f5a786041a87a7d45f4ec5
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10555
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
1 file changed