pimd: Fix leaked fd

When caling pim_sock_open if the failure cause happens, however
unlikely, don't leak the fd on failure.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/pimd/pim_pim.c b/pimd/pim_pim.c
index 41c26a8..cd8a290 100644
--- a/pimd/pim_pim.c
+++ b/pimd/pim_pim.c
@@ -371,6 +371,7 @@
     return -1;
 
   if (pim_socket_join(fd, qpim_all_pim_routers_addr, ifaddr, ifindex)) {
+    close(fd);
     return -2;
   }