middle-end/98974 - fixup after STMT_VINFO_VEC_STMTS rework

middle-end/98974 - fixup after STMT_VINFO_VEC_STMTS rework

This fixes up the nvectors parameter passed to vect_get_loop_mask in
vectorizable_condition after the STMT_VINFO_VEC_STMTS rework.

gcc/ChangeLog:
2021-02-08  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR middle-end/98974
	* tree-vect-stmts.c (vectorizable_condition): Remove shadow vec_num
	parameter in vectorizable_condition.

gcc/testsuite/ChangeLog:
2021-02-08  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	PR middle-end/98974
	* gfortran.dg/pr98974.F90: New test.