needed changes to support glEGLImageTargetRenderbufferStorageOES,
added implementation in egl and added tokens to renderControl.
Also fixed function pointers returned by eglGetProcAddress to
return functions that works independant of the current context,
see system/egl/ClientAPIExts.cpp
That makes the egl_image conformance test to pass on the guest.
Change-Id: I580cda82ba0fb44f12b75aa0bbacf5cd9f15f744
