OpenACC/Fortran: permit 'routine' inside PURE

OpenACC/Fortran: permit 'routine' inside PURE

gcc/fortran/ChangeLog

	* parse.c (decode_oacc_directive): Permit 'acc routine' also
	inside pure procedures.
	* openmp.c (gfc_match_oacc_routine): Inside pure procedures
	do not permit gang, worker or vector clauses.

libgomp/ChangeLog:

	* testsuite/libgomp.oacc-fortran/routine-10.f90: New test.

gcc/testsuite/ChangeLog:

	* gfortran.dg/goacc/pure-elemental-procedures-2.f90: New test.

Reviewed-by: Thomas Schwinge <thomas@codesourcery.com>