allow using socket to connect to mysql

split the socket from port if hostname contains colon
this also allows $port to be just path to socket (not-numeric)

localhost:/tmp/sock inspired by:
http://bugs.cacti.net/view.php?id=425

note: this socket works for mysqli driver only:
http://phplens.com/lens/adodb/docs-adodb.htm


--- cacti-0.8.7i-PIA-3.1/lib/database.php~	2011-12-12 03:56:06.000000000 +0200
+++ cacti-0.8.7i-PIA-3.1/lib/database.php	2012-01-24 11:18:39.563094454 +0200
@@ -34,6 +34,11 @@
 function db_connect_real($host, $user, $pass, $db_name, $db_type, $port = "3306", $db_ssl = false, $retries = 20) {
 	global $cnn_id;
 
+	// convert hostname:port to hostname and port
+	if (strchr($host, ':')) {
+		list($host, $port) = explode(':', $host, 2);
+	}
+
 	$i = 0;
 	$dsn = "$db_type://" . rawurlencode($user) . ":" . rawurlencode($pass) . "@" . rawurlencode($host) . "/" . rawurlencode($db_name) . "?persist";
 
@@ -43,7 +48,10 @@
 		$dsn .= "&clientflags=" . MYSQLI_CLIENT_SSL;
 	}
 
-	if ($port != "3306") {
+	// socket supported for mysqli only, not mysql
+	if ($port && !is_numeric($port)) {
+		$dsn .= "&socket=" . $port;
+	} elseif ($port != "3306") {
 		$dsn .= "&port=" . $port;
 	}