vppapigen: support per-file (major,minor,patch) version stamps

Add one of these statements to foo.api:

  vl_api_version 1.2.3

to generate a version tuple stanza in foo.api.h:

/****** Version tuple *****/

vl_api_version_tuple(foo, 1, 2, 3)

Change-Id: Ic514439e4677999daa8463a94f948f76b132ff15
Signed-off-by: Dave Barach <dave@barachs.net>
Signed-off-by: Ole Troan <ot@cisco.com>
diff --git a/src/vlibapi/api.h b/src/vlibapi/api.h
index 49f5d5f..6820a54 100644
--- a/src/vlibapi/api.h
+++ b/src/vlibapi/api.h
@@ -114,6 +114,8 @@
 				      vl_api_trace_which_t which);
 void vl_msg_api_add_msg_name_crc (api_main_t * am, const char *string,
 				  u32 id);
+void vl_msg_api_add_version (api_main_t * am, const char *string,
+			     u32 major, u32 minor, u32 patch);
 /* node_serialize.c prototypes */
 u8 *vlib_node_serialize (vlib_node_main_t * nm, u8 * vector,
 			 u32 max_threads, int include_nexts,