c-parser.c (c_parser_omp_atomic): Allow seq_cst before atomic-clause...

c-parser.c (c_parser_omp_atomic): Allow seq_cst before atomic-clause...

gcc/c/
	* c-parser.c (c_parser_omp_atomic): Allow seq_cst before
	atomic-clause, allow comma in between atomic-clause and
	seq_cst.
gcc/cp/
	* parser.c (cp_parser_omp_atomic): Allow seq_cst before
	atomic-clause, allow comma in between atomic-clause and
	seq_cst.
gcc/testsuite/
	* c-c++-common/gomp/atomic-16.c: Remove all dg-error directives.
	Replace load with read and store with write.
libgomp/
	* testsuite/libgomp.c++/atomic-14.C: Allow seq_cst and
	atomic type clauses in any order and optional comma in between.
	* testsuite/libgomp.c++/atomic-15.C: Likewise.
	* testsuite/libgomp.c/atomic-17.c: Likewise.

From-SVN: r209762