tree-optimization/104267 - fix external def vector type for call args

tree-optimization/104267 - fix external def vector type for call args

The following fixes the vector type registered for external defs
in call arguments when vectorizing with SLP.  We assumed uniform
vectype_in types here but with calls like .COND_MUL we also have
mask arguments which, when invariant or external, need to have
a proper mask vector type.

2022-01-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/104267
	* tree-vect-stmts.cc (vectorizable_call): Properly use the
	per-argument determined vector type for externals and
	invariants.