Fix 5.5.10 NEWS

The FPM change didn't make it into 5.5.10 but will instead be in 5.5.11; http://php.net/Changelog-5.php, the release and the NEWS file in the release accurately reflect this, but the 5.5 branch NEWS doesn't (as the release was made and tagged from the last RC, which didn't contain that change yet). Refs GitHub PR #598.