Test what OpenMP 5.0 has to say on this topic.  And, do the same for OpenACC.

	libgomp/
	PR fortran/90743
	* oacc-parallel.c (GOACC_parallel_keyed): Handle NULL mapping
	case.
	* testsuite/libgomp.fortran/target-allocatable-1-1.f90: New file.
	* testsuite/libgomp.fortran/target-allocatable-1-2.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/allocatable-1-1.f90: Likewise.
	* testsuite/libgomp.oacc-fortran/allocatable-1-2.f90: Likewise.

From-SVN: r272447