* scripts/check_performance: Only compile with $THREAD_FLAG
	when test is marked to require it.  Allow multiple
	compilations/executions of marked tests.
	* testsuite/testsuite_performance.h (report_performance):
	Report dynamic thread support status.
	(report_header): Likewise.
	* testsuite/performance/allocator.cc: Stabilize iteration
	count.  Support more allocators.  Mark each allocator test to
	run and report independently.
	* testsuite/performance/allocator_map_thread.cc: Likewise.
	* testsuite/performance/allocator_thread.cc: Likewise.

From-SVN: r76932