Add ES3 functions and constants, difficult ones commented out

This change adds ES3 functions to GLES30.spec, disabling any that
require non-trivial changes for the generator to handle.

Steps taken to add these:
- Copy ES3 function declarations from gl3.h
- Remove GL_APICALL, GL_APIENTRY, and semicolon from each declaration
- Add whitespace around parens and *s as required by the parser
- Comment out functions that the generator doesn't understand or that
  it generates bad Java interfaces for (by inspection).

Bug: 8566953
Change-Id: Iaaef7d53e24f9a576759dbba72cd206bae1c1276