OpenACC 'acc_get_property' cleanup

	include/
	* gomp-constants.h (enum gomp_device_property): Remove.
	libgomp/
	* libgomp-plugin.h (enum goacc_property): New.  Adjust all users
	to use this instead of 'enum gomp_device_property'.
	(GOMP_OFFLOAD_get_property): Rename to...
	(GOMP_OFFLOAD_openacc_get_property): ... this.  Adjust all users.
	* libgomp.h (struct gomp_device_descr): Move
	'GOMP_OFFLOAD_openacc_get_property'...
	(struct acc_dispatch_t): ... here.  Adjust all users.
	* plugin/plugin-hsa.c (GOMP_OFFLOAD_get_property): Remove.
	liboffloadmic/
	* plugin/libgomp-plugin-intelmic.cpp (GOMP_OFFLOAD_get_property):
	Remove.

From-SVN: r280150