[Tizen] Apply only Enabling Hardware Acceleration with Libva and EGL in Tizen

Since the (Refer to: https://github.com/crosswalk-project/crosswalk/pull/892) had been merged, this pull request will apply to chromium-crosswalk that and make Tizen VAVDA solution available.

Also, This PR will fix the "./libva/" not be included into ./gpu/, which will cause compiling fails during without "share_library" type of building from PR#892.


Why we need to maintain it in our side:

1) Upstream confirm VAVDA will continue to be restricted to
   CrOS/X86 for dev & testing only and not for chromium road map.
2) CrOS/X86 no plan to expend EGL backend which finalize in
   June 2012 and be addressed to the CrOS graphics team.

So, the upstream no plan to lerage VAVDA with EGL graphic
   backend for any X86.

3) The tizen-mobile's driver only support EGL as texture
   backend. The video hw acceleration of xwalk have to
   rely on EGL not GLX to bind decoded pixmap.

That's why we enable specific EGL for VAVDA in tizen port.