openmp: Fix parallel master error recovery [PR94512]

openmp: Fix parallel master error recovery [PR94512]

We need to set OMP_PARALLEL_COMBINED only if the parsing of omp_master
succeeded, because otherwise there is no nested master construct in the
parallel.

2020-04-07  Jakub Jelinek  <jakub@redhat.com>

	PR c++/94512
	* c-parser.c (c_parser_omp_parallel): Set OMP_PARALLEL_COMBINED
	if c_parser_omp_master succeeded.

	* parser.c (cp_parser_omp_parallel): Set OMP_PARALLEL_COMBINED
	if cp_parser_omp_master succeeded.

	* g++.dg/gomp/pr94512.C: New test.