Update 'c-c++-common/goacc/classify-*', 'gfortran.dg/goacc/classify-*'

... to use 'dg-line', simplifying later changes.  Also some minor miscellaneous
diagnostics scanning maintenance.

	gcc/testsuite/
	* c-c++-common/goacc/classify-kernels-parloops.c: Update.
	* c-c++-common/goacc/classify-kernels-unparallelized-parloops.c:
	Likewise.
	* c-c++-common/goacc/classify-kernels-unparallelized.c: Likewise.
	* c-c++-common/goacc/classify-kernels.c: Likewise.
	* c-c++-common/goacc/classify-parallel.c: Likewise.
	* c-c++-common/goacc/classify-routine-nohost.c: Likewise.
	* c-c++-common/goacc/classify-routine.c: Likewise.
	* c-c++-common/goacc/classify-serial.c: Likewise.
	* gfortran.dg/goacc/classify-kernels-parloops.f95: Likewise.
	* gfortran.dg/goacc/classify-kernels-unparallelized-parloops.f95:
	Likewise.
	* gfortran.dg/goacc/classify-kernels-unparallelized.f95: Likewise.
	* gfortran.dg/goacc/classify-kernels.f95: Likewise.
	* gfortran.dg/goacc/classify-parallel.f95: Likewise.
	* gfortran.dg/goacc/classify-routine-nohost.f95: Likewise.
	* gfortran.dg/goacc/classify-routine.f95: Likewise.
	* gfortran.dg/goacc/classify-serial.f95: Likewise.