[Patch 0/5 v2] Improve wayland-drm to wayland-gbm to act as generic buffer manager for wayland

[Zhao, Halley]

== version 2:
  - follow Gwenole's feed back to change wayland_gbm_* to wl_gbm_*
  - use Evolution to send the patch (some previous patches sent from
outlook are blocked)
  - add patch 5 to change file names from *drm* to *gbm*

== original patch information 
EGL implements wayland-drm protocol, however, it hasn't been used by
vappi yet since EGL doesn't export wl_drm(bnf think it is bad style).

After some thought, I improve wayland-drm to base on gbm instead.
The module name changes to wayland-gbm as well, gbm is platform
independent, Expect it will be ok to export wl_gbm through libEGL.