php/add-php-ref-handling: Be careful to pick up just the parameter
name and not any default value.  (Fixes #659, reported by jmienert)
php/smoketest.php: Add regression test.

git-svn-id: file:///home/xapian-svn/xapian/trunk@18277 6b2f1b92-a4f3-0310-943f-de3cbe41748b