Add OpenGL ES 3.0 entry function stubs.

Bug 19353461

Change-Id: Ib48ae3263a1a570067dc0bc9a3dd2252f5a282a3
Reviewed-on: https://swiftshader-review.googlesource.com/2191
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>