handle clang's option "-meabi gnu"
Clang has an option "-meabi <arg>" which is used by the kernel for ARMv7.
This kind of option, taking a argument without a separating '=', can't
be ignored like most other options and must this be special-cased.
So, add the special case for this option and consume the argument if it's
one of the valid one.
Link: https://lore.kernel.org/r/20220331110118.vr4miyyytqlssjoi@pengutronix.de
Reported-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>