openmp: Fix reduction clause handling on teams distribute simd [PR99928]

openmp: Fix reduction clause handling on teams distribute simd [PR99928]

When a directive isn't combined with worksharing-loop, it takes much
simpler clause splitting path for reduction, and that one was missing
handling of teams when combined with simd.

2021-05-25  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/99928
gcc/c-family/
	* c-omp.c (c_omp_split_clauses): Copy reduction to teams when teams is
	combined with simd and not with taskloop or for.
gcc/testsuite/
	* c-c++-common/gomp/pr99928-8.c: Remove xfails from omp teams r21 and
	r28 checks.
	* c-c++-common/gomp/pr99928-9.c: Likewise.
	* c-c++-common/gomp/pr99928-10.c: Likewise.
libgomp/
	* testsuite/libgomp.c-c++-common/reduction-17.c: New test.