[cmf] update the way constants are handled in data/php_stdlib/

Summary: Hphp people have changed (again) the way builtins are handled.

Test Plan:
cd pfff/data/php_stdlib
make update
make check
 see no dupes
also some recent builtins mentioned in phabricator lint errors such
 as JSON_PRETTY_PRINT are in the generate system/constants.php file

Reviewers: jwatzman, pieter

Reviewed By: jwatzman

CC: sgolemon, neal, bryano, ps, erling

Differential Revision: https://phabricator.fb.com/D1174028
[pfff] support the new X:class php 5.5 extension

Test Plan:
unit tests included
make tests

Reviewers: eletuchy, jwatzman, julienv, jcreed

CC: bryano, amenghra, platform-diffs@lists

Differential Revision: https://phabricator.fb.com/D1174832