crossgcc/Makefile: Allow making toolchains using multiple cores

I looked for a way to pass the 'make crossgcc -j8' on to buildgcc, but
didn't find a way to get that value directly.  MAKEFLAGS turns -j8 into
a jobserver variable.

Instead, this patch allows the number of CPUs to be set on the command
line through a variable instead.

Example: 'make crossgcc BUILDJOBS=8'

Change-Id: I37608cdb4549226cb7ff8c3ff6d9f4773acf6b0b
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: http://review.coreboot.org/10620
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed