This patch adds the OpenACC 2.5 new APIs of acc_get_default_async/acc_set_default_async,
contained are the modifications for Fortran in libgomp/openacc.f90, libgomp/openacc_lib.h,
and a small testsuite adjustment.

Thanks,
Chung-Lin

	* openacc.f90 (acc_async_default): Declare.
	(acc_set_default_async): Likewise.
	(acc_get_default_async): Likewise.
  	* openacc_lib.h (acc_async_default): Declare.
  	(acc_set_default_async): Likewise.
	(acc_get_default_async): Likewise.

	* testsuite/libgomp.oacc-fortran/lib-12.f90: Likewise.