[PR88484] OpenACC wait directive without wait argument but with async clause

[PR88484] OpenACC wait directive without wait argument but with async clause

We don't correctly handle "#pragma acc wait async (a)" for "a >= 0", handling
as a no-op whereas it should enqueue the appropriate wait operations on
"async (a)".

	libgomp/
	PR libgomp/88484
	* oacc-parallel.c (GOACC_wait): Correct handling for "async >= 0".
	* testsuite/libgomp.oacc-c-c++-common/asyncwait-nop-1.c: New file.

From-SVN: r267151