Makefile: add -Wsign-compare to warning options

Now that all signedness comparison warnings in the source tree have been
fixed, let's enable the warning option, to avoid them creeping in again.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Message-Id: <20210618172030.9684-6-andre.przywara@arm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed