This patch separates out the header interface changes. GOMP_VERSION has been bumped,
and various changes to the plugin interface, and a few libgomp internal functions
declared. The libgomp linkmap updated as well.

Thanks,
Chung-Lin

	include/
	* gomp-constants.h (GOMP_ASYNC_DEFAULT): Define.
	(GOMP_VERSION): Increment for new plugin interface changes.

	libgomp/
	* libgomp-plugin.h (struct goacc_asyncqueue): Declare.
	(struct goacc_asyncqueue_list): Likewise.
	(goacc_aq): Likewise.
	(goacc_aq_list): Likewise.
	(GOMP_OFFLOAD_openacc_register_async_cleanup): Remove.
	(GOMP_OFFLOAD_openacc_async_test): Remove.
	(GOMP_OFFLOAD_openacc_async_test_all): Remove.
	(GOMP_OFFLOAD_openacc_async_wait): Remove.
	(GOMP_OFFLOAD_openacc_async_wait_async): Remove.
	(GOMP_OFFLOAD_openacc_async_wait_all): Remove.
	(GOMP_OFFLOAD_openacc_async_wait_all_async): Remove.
	(GOMP_OFFLOAD_openacc_async_set_async): Remove.
	(GOMP_OFFLOAD_openacc_exec): Adjust declaration.
	(GOMP_OFFLOAD_openacc_cuda_get_stream): Likewise.
	(GOMP_OFFLOAD_openacc_cuda_set_stream): Likewise.

	(GOMP_OFFLOAD_openacc_async_exec): Declare.
	(GOMP_OFFLOAD_openacc_async_construct): Declare.
	(GOMP_OFFLOAD_openacc_async_destruct): Declare.
	(GOMP_OFFLOAD_openacc_async_test): Declare.
	(GOMP_OFFLOAD_openacc_async_synchronize): Declare.
	(GOMP_OFFLOAD_openacc_async_serialize): Declare.
	(GOMP_OFFLOAD_openacc_async_queue_callback): Declare.
	(GOMP_OFFLOAD_openacc_async_host2dev): Declare.
	(GOMP_OFFLOAD_openacc_async_dev2host): Declare.

	* libgomp.h (struct acc_dispatch_t): Define 'async' sub-struct.
	(gomp_acc_insert_pointer): Adjust declaration.
	(gomp_copy_host2dev): New declaration.
	(gomp_copy_dev2host): Likewise.
	(gomp_map_vars_async): Likewise.
	(gomp_unmap_tgt): Likewise.
	(gomp_unmap_vars_async): Likewise.
	(gomp_fini_device): Likewise.

	* libgomp.map (OACC_2.5): Add acc_get_default_async,
	acc_get_default_async_h_, acc_set_default_async, and
	acc_set_default_async_h_.
	(GOMP_PLUGIN_1.0): Remove GOMP_PLUGIN_async_unmap_vars.