Fixes for querying things out of cubemaps
Create meshVAO on replay context, early out if no VB is bound
Call GetRealFunctions on MakeCurrent to populate extensions.

* Even if the app only queries some subset of extensions, we may need
  more (e.g. need the DSA extensions). GetRealFunctions does a
  PopulateHooks which will fill out the extensions that we need.
Intercept any DrawBuffers enums and convert GL_BACK/GL_FRONT
Only look up live resource when not writing
Set eTextureCreate_SwapBuffer property properly
Check creation flags to see if it's backbuffer color, not name
Set BufferRecords in the right spot, before serialising