don't replace with ?, just skip it
Merge branch 'PHP-5.5' into PHP-5.6

Conflicts:
	ext/mysqli/mysqli_api.c
Emit a warning in case of unallowed characters. Fix another place this
code is used - reuse
Merge branch 'PHP-5.5' into PHP-5.6
Fixes after merge
Merge branch 'PHP-5.6' of git.php.net:php-src into PHP-5.6