gas used to accept (and ignore?) .size directives which referred to
undefined symbols, as these do.  In binutils 2.21 these are treated
as fatal errors.

The issue in proc-arm7tdmi.S was also fixed independently by Peter
Chubb.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>