[ticket/12794] Properly validate google+ field against valid character set

PHPBB3-12794

phpBB/phpbb/profilefields/type/type_googleplus.php

@@ -40,7 +40,7 @@ class type_googleplus extends type_string
 			'field_length'			=> 20,
 			'field_minlen'			=> 3,
 			'field_maxlen'			=> 255,
-			'field_validation'		=> '[\w]+',
+			'field_validation'		=> '(?:(?!\.{2,})([^<>=+]))+',
 			'field_novalue'			=> '',
 			'field_default_value'	=> '',
 		);