vect: allow using inbranch simdclones for masked loops

vect: allow using inbranch simdclones for masked loops

In a previous patch I did most of the work for this, but forgot to change the
check for number of arguments matching between call and simdclone.  This check
should accept calls without a mask to be matched against simdclones with mask
arguments.  I also added tests to verify this feature actually works.

gcc/ChangeLog:

	* tree-vect-stmts.cc (vectorizable_simd_clone_call): Allow unmasked
	calls to use masked simdclones.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/vect-simd-clone-20.c: New file.
	* gfortran.dg/simd-builtins-1.h: Adapt.
	* gfortran.dg/simd-builtins-6.f90: Adapt.