Move 'libgomp/oacc-parallel.c:GOACC_declare' into 'libgomp/oacc-mem.c'

This deals with data management, after all.

Small fix-up for r230275 (commit 6e232ba4246ca324a663ec5ddf0ba4db5cf3fbad)
"[OpenACC] declare directive".

	libgomp/
	* oacc-parallel.c (GOACC_declare): Move...
	* oacc-mem.c: ... here.
	* libgomp_g.h: Adjust.
3 files changed