Update PHP compatibility information

Summary: Update php_compat_info.json using PHP CompatInfo version 4.1. In particular, this adds compatibility information for class methods (even though we don't currently use this information).

Test Plan: Eyeballed the changes, seems legit.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12874