libgomp: 'libgomp/config/nvptx/oacc-parallel.c' -> 'libgomp/config/accel/oacc-parallel.c'

For no good reason, libgomp/GCN currently compiles the "full" (host)
'oacc-parallel.c', instead of the empty "accel" one.  Minor fix-up for
Subversion r278132 (Git commit b3d14b3aa343eb7fc656e7f4d3c9b2dc04be63be)
"Move generic libgomp files from nvptx to accel", which moved other files
from 'libgomp/config/nvptx/' to 'libgomp/config/accel/'.

	libgomp/
	* config/nvptx/oacc-parallel.c: Move...
	* config/accel/oacc-parallel.c: ... here.

diff --git a/libgomp/config/nvptx/oacc-parallel.c b/libgomp/config/accel/oacc-parallel.c
similarity index 100%
rename from libgomp/config/nvptx/oacc-parallel.c
rename to libgomp/config/accel/oacc-parallel.c