[Libva] Gstreamer-vaapi: about the option --with-gstreamer-api

[Lim, Siew Hoon]

> Should be fine I think...
> Please provide the patch through bugzilla:
> https://bugzilla.gnome.org/enter_bug.cgi?product=gstreamer-vaapi
> 

Done. 
https://bugzilla.gnome.org/show_bug.cgi?id=753618

Patch also attached inside the Bugzilla.

Thanks.
....siewhoon