virNetDevOpenvswitchGetVhostuserIfname: Fix off by one error

https://bugzilla.redhat.com/show_bug.cgi?id=1459091

We try to get the last element of the passed path by calling
strrch(path, '/'). However, the pointer that strrchr() returns
points at the slash, We want string that starts right after that.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/util/virnetdevopenvswitch.c

@@ -444,6 +444,7 @@ virNetDevOpenvswitchGetVhostuserIfname(const char *path,
         goto cleanup;
     }
 
+    tmpIfname++;
     cmd = virCommandNew(OVSVSCTL);
     virNetDevOpenvswitchAddTimeout(cmd);
     virCommandAddArgList(cmd, "get", "Interface", tmpIfname, "name", NULL);