backport: re PR c/51360 (spurious unused-but-set-variable warning for var used in...

backport: re PR c/51360 (spurious unused-but-set-variable warning for var used in OpenMP pragma)

	Backported from mainline
	2011-12-15  Jakub Jelinek  <jakub@redhat.com>

	PR c/51360
	* c-parser.c (c_parser_omp_clause_num_threads,
	c_parser_omp_clause_schedule): Call mark_exp_read.

	* semantics.c (finish_omp_clauses): For OMP_CLAUSE_NUM_THREADS_EXPR
	and OMP_CLAUSE_SCHEDULE_CHUNK_EXPR call mark_rvalue_use.

	* gcc.dg/gomp/pr51360.c: New test.
	* g++.dg/gomp/pr51360.C: New test.
	* g++.dg/gomp/pr51360-2.C: New test.

From-SVN: r184049