[Vect] Fix mask check on Scatter loads/stores

[Vect] Fix mask check on Scatter loads/stores

Previously, IFN_MASK_SCATTER_STORE was used if 'loop_masks' was
non-null, but the mask used is 'final_mask'. This caused a bug where
a 'MASK_STORE' was vectorized into a 'SCATTER_STORE' instead of a
'MASK_SCATTER_STORE'. This fixes PR target/99102.

gcc/ChangeLog:

	PR target/99102
	* tree-vect-stmts.c (vectorizable_store): Fix scatter store mask
	check condition.
	(vectorizable_load): Fix gather load mask check condition.

gcc/testsuite/ChangeLog:

	PR target/99102
	* gcc.dg/vect/pr99102.c: New test.