This adds a library that can be used instead of libGLESv2.so to provide
symbols for the GLES 2.0 api. This can be used for convenience when
using the cogl_gles2_context_ api since you don't need to manually go
through a CoglGLES2Vtable when calling the gles2 api so it should be
easier to port existing gles2 code to integrate with Cogl.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 80d7599a2acefca7d01d8d7de9df524278ef72c5)
