parallels: increment the number of connection drivers

We need to do this because we have just added a vz driver.
Signed-off-by: NMaxim Nestratov <mnestratov@parallels.com>

src/libvirt.c

@@ -109,7 +109,7 @@ VIR_LOG_INIT("libvirt");
  * - use reference counting to guarantee coherent pointer state ?
  */
 
-#define MAX_DRIVERS 20
+#define MAX_DRIVERS 21
 
 static virConnectDriverPtr virConnectDriverTab[MAX_DRIVERS];
 static int virConnectDriverTabCount;