slp: check that the operation we're combing is a boolean operation [PR103741]

slp: check that the operation we're combing is a boolean operation [PR103741]

It seems I forgot to check that the operation we're combing when masking the
predicated together are actually predicates types.

Without it we end up accidentally trying to combine a value and a mask.

gcc/ChangeLog:

	PR tree-optimization/103741
	* tree-vect-stmts.c (vectorizable_operation): Check for boolean.

gcc/testsuite/ChangeLog:

	PR tree-optimization/103741
	* gcc.target/aarch64/pr103741.c: New test.