network: fix incorrect VIR_NETWORK_UPDATE_COMMAND_* values

These enums originally were put into the flags for virNetworkUpdate,
and when they were moved into their own enum, the numbers weren't
appropriately changed, causing the commands to start with value 2
instead of 1. This causes problems for things like ENUM_IMPL, which
wants a string for every value in the requested range, including those
not used in the enum.

include/libvirt/libvirt.h.in

@@ -2356,10 +2356,10 @@ int                     virNetworkUndefine      (virNetworkPtr network);
  */
 typedef enum {
     VIR_NETWORK_UPDATE_COMMAND_NONE      = 0, /* (invalid) */
-    VIR_NETWORK_UPDATE_COMMAND_MODIFY    = 2, /* modify an existing element */
-    VIR_NETWORK_UPDATE_COMMAND_DELETE    = 3, /* delete an existing element */
-    VIR_NETWORK_UPDATE_COMMAND_ADD_LAST  = 4, /* add an element at end of list */
-    VIR_NETWORK_UPDATE_COMMAND_ADD_FIRST = 5, /* add an element at start of list */
+    VIR_NETWORK_UPDATE_COMMAND_MODIFY    = 1, /* modify an existing element */
+    VIR_NETWORK_UPDATE_COMMAND_DELETE    = 2, /* delete an existing element */
+    VIR_NETWORK_UPDATE_COMMAND_ADD_LAST  = 3, /* add an element at end of list */
+    VIR_NETWORK_UPDATE_COMMAND_ADD_FIRST = 4, /* add an element at start of list */
 #ifdef VIR_ENUM_SENTINELS
     VIR_NETWORK_UPDATE_COMMAND_LAST
 #endif