[openacc] Add used parameter to TARGET_GOACC_VALIDATE_DIMS

[openacc] Add used parameter to TARGET_GOACC_VALIDATE_DIMS

Add a used parameter to TARGET_GOACC_VALIDATE_DIMS, allowing a target to make
decisions in the hook implementation based on whether a dimension is used or
not.

2019-01-12  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.c (nvptx_goacc_validate_dims_1)
	(nvptx_goacc_validate_dims): Add used parameter.
	* doc/tm.texi: Regenerate.
	* omp-offload.c (oacc_parse_default_dims, oacc_validate_dims): Add
	argument to call to targetm.goacc.validate_dims.
	(default_goacc_validate_dims): Add used
	parameter.
	* target.def (validate_dims): Add used parameter in DEFHOOK.
	* targhooks.h (default_goacc_validate_dims): Add used parameter.

From-SVN: r267876