libgomp nvptx plugin: rework initialisation and support the proposed load/unload hooks (was: Merge current set of OpenACC changes from gomp-4_0-branch)

[Jakub Jelinek]

On Wed, Apr 08, 2015 at 03:31:42PM +0100, Julian Brown wrote:
> It passes libgomp testing on NVPTX. OK?

Please write a proper ChangeLog entry for it.
Ok with that.

	Jakub