This patch adds *_async versions of several OpenACC runtime library API functions,
which is to allow execution of a function asynchronously on particular async
stream, an addition to the standard since 2.5. Specifically, these functions:

acc_copyin_async
acc_copyout_async
acc_copyout_finalize_async
acc_create_async
acc_delete_async
acc_delete_finalize_async
acc_memcpy_from_device_async
acc_memcpy_to_device_async
acc_update_device_async
acc_update_self_async

which have an additional 'int async' argument in additional from the non-async version.

libgomp tested with offloading with no regressions, is this okay for trunk?

Thanks,
Chung-Lin

2018-09-10  Chung-Lin Tang  <cltang@codesourcery.com>

         libgomp/
         * oacc-mem.c (memcpy_tofrom_device): New function, combined from
         acc_memcpy_to/from_device functions, now with async parameter.
         (acc_memcpy_to_device): Modify to use memcpy_tofrom_device.
         (acc_memcpy_from_device): Likewise.
         (acc_memcpy_to_device_async): New API function.
         (acc_memcpy_from_device_async): Likewise.
         (present_create_copy): Add async parameter and async setting/unsetting.
         (acc_create): Adjust present_create_copy call.
         (acc_copyin): Likewise.
         (acc_present_or_create): Likewise.
         (acc_present_or_copyin): Likewise.
         (acc_create_async): New API function.
         (acc_copyin_async): New API function.
         (delete_copyout): Add async parameter and async setting/unsetting.
         (acc_delete): Adjust delete_copyout call.
         (acc_copyout): Likewise.
         (acc_delete_async): New API function.
         (acc_copyout_async): Likewise.
         (update_dev_host): Add async parameter and async setting/unsetting.
         (acc_update_device): Adjust update_dev_host call.
         (acc_update_self): Likewise.
         (acc_update_device_async): New API function.
         (acc_update_self_async): Likewise.
         * openacc.h (acc_copyin_async): Declare new API function.
         (acc_create_async): Likewise.
         (acc_copyout_async): Likewise.
         (acc_delete_async): Likewise.
         (acc_update_device_async): Likewise.
         (acc_update_self_async): Likewise.
         (acc_memcpy_to_device_async): Likewise.
         (acc_memcpy_from_device_async): Likewise.
         * openacc_lib.h (acc_copyin_async_32_h): New subroutine.
         (acc_copyin_async_64_h): New subroutine.
         (acc_copyin_async_array_h): New subroutine.
         (acc_create_async_32_h): New subroutine.
         (acc_create_async_64_h): New subroutine.
         (acc_create_async_array_h): New subroutine.
         (acc_copyout_async_32_h): New subroutine.
         (acc_copyout_async_64_h): New subroutine.
         (acc_copyout_async_array_h): New subroutine.
         (acc_delete_async_32_h): New subroutine.
         (acc_delete_async_64_h): New subroutine.
         (acc_delete_async_array_h): New subroutine.
         (acc_update_device_async_32_h): New subroutine.
         (acc_update_device_async_64_h): New subroutine.
         (acc_update_device_async_array_h): New subroutine.
         (acc_update_self_async_32_h): New subroutine.
         (acc_update_self_async_64_h): New subroutine.
         (acc_update_self_async_array_h): New subroutine.
         * openacc.f90 (acc_copyin_async_32_h): New subroutine.
         (acc_copyin_async_64_h): New subroutine.
         (acc_copyin_async_array_h): New subroutine.
         (acc_create_async_32_h): New subroutine.
         (acc_create_async_64_h): New subroutine.
         (acc_create_async_array_h): New subroutine.
         (acc_copyout_async_32_h): New subroutine.
         (acc_copyout_async_64_h): New subroutine.
         (acc_copyout_async_array_h): New subroutine.
         (acc_delete_async_32_h): New subroutine.
         (acc_delete_async_64_h): New subroutine.
         (acc_delete_async_array_h): New subroutine.
         (acc_update_device_async_32_h): New subroutine.
         (acc_update_device_async_64_h): New subroutine.
         (acc_update_device_async_array_h): New subroutine.
         (acc_update_self_async_32_h): New subroutine.
         (acc_update_self_async_64_h): New subroutine.
         (acc_update_self_async_array_h): New subroutine.
         * libgomp.map (OACC_2.5): Add acc_copyin_async*, acc_copyout_async*,
         acc_copyout_finalize_async*, acc_create_async*, acc_delete_async*,
         acc_delete_finalize_async*, acc_memcpy_from_device_async*,
         acc_memcpy_to_device_async*, acc_update_device_async*, and
         acc_update_self_async* entries.
         * testsuite/libgomp.oacc-c-c++-common/lib-94.c: New test.
         * testsuite/libgomp.oacc-c-c++-common/lib-95.c: New test.
         * testsuite/libgomp.oacc-fortran/lib-16.f90: New test.