toolchain: fix build with x86_64 gcc

Commit f69a99db (coreboot: x86: enable gc-sections) overrides
CFLAGS_x86_32, which looses (among other things) -m32, which
in turn breaks the build with the standard distro gcc on a
x86_64 machine.

Fix it by appending the new flags instead.

Change-Id: Ic3409a1aaa5b26139847258a7eb5c3468efdc6a3
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-on: http://review.coreboot.org/9053
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>
1 file changed