xcompile: actually use "special compile flags" idea

xcompile used to test for special ARM flags - that were
Meanwhile, -Wa,--divide, which is only useful on i386-elf
was tested for on arm and aarch64, too

Change-Id: I1a5a1bc40fa1040d0939038b073aef31c72d0c6f
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/5743
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed