Fix an uninitialized variable in Unix socket open

* src/qemu_driver.c: qemudOpenMonitorUnix() had an uninitialized loop
  counter

src/qemu_driver.c

@@ -874,7 +874,7 @@ qemudOpenMonitorUnix(virConnectPtr conn,
     struct sockaddr_un addr;
     int monfd;
     int timeout = 3; /* In seconds */
-    int ret, i;
+    int ret, i = 0;
 
     if ((monfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
         virReportSystemError(conn, errno,