flex is needed by acpica. This patch makes the build fail early
instead of after gcc has been compiled, if flex is not there.
Change-Id: Idfd71bdf704ab25de655f1a72c266c5220b15048
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/1860
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>