vlib: improve exec path search

Fixes VPP invocation with relative path, i.e.:

$ bin/vpp unix interactive

Type: improvement
Change-Id: I0278710bb472b92e31389b2d28955c3d33550230
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/cli.c b/src/vlib/cli.c
index 2187d28..b7c4c00 100644
--- a/src/vlib/cli.c
+++ b/src/vlib/cli.c
@@ -1097,7 +1097,7 @@
   /* *INDENT-ON* */
 
   /* Exec ourself */
-  execve (vgm->name, (char **) vm->argv, environ);
+  execve (vgm->name, (char **) vgm->argv, environ);
 
   return 0;
 }