lib: bump ZSERV_VERSION to 2

continually changing the zserv protocol without bumping up the version
number has made it impossible to talk to zebra without knowing the exact
version.  in reality, increasing the version number more often guards
against inadvertedly running incompatible versions of a daemon and zebra
as well as aids external development.

  * lib/zclient.h: #define ZSERV_VERSION 2

Signed-off-by: David Lamparter <equinox@diac24.net>
diff --git a/lib/zclient.h b/lib/zclient.h
index a7d7b54..a660bbf 100644
--- a/lib/zclient.h
+++ b/lib/zclient.h
@@ -98,7 +98,7 @@
                          * always set to 255 in new zserv.
                          */
   uint8_t version;
-#define ZSERV_VERSION	1
+#define ZSERV_VERSION	2
   uint16_t command;
 };