Dear all,

we need to check the arguments of the elemental MASKL and MASKR
intrinsics also before simplifying.

Testcase by Gerhard.  The fix is almost obvious, but I'm happy to
get feedback in case there is something I overlooked.  (There is
already a check on scalar arguments to MASKL/MASKR, which however
misses the case of array arguments.)

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald