FIB: crash when deleting default route

when adding a recursive path the table is locked
so that it can be removed when the last recursive path
is removed. however, not all RR source'd prefixs use
a recursive path. so flushing the table of all RR source'd
entries is not correct.

Change-Id: Id4010774011046e66ddc443ac83cb8e9245313dd
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/fib/fib_table.c b/src/vnet/fib/fib_table.c
index f46a5b4..56c8f03 100644
--- a/src/vnet/fib/fib_table.c
+++ b/src/vnet/fib/fib_table.c
@@ -1244,15 +1244,6 @@
     fib_table->ft_locks[source]--;
     fib_table->ft_locks[FIB_TABLE_TOTAL_LOCKS]--;
 
-    if (0 == fib_table->ft_locks[source])
-    {
-        /*
-         * The source no longer needs the table. flush any routes
-         * from it just in case
-         */
-        fib_table_flush(fib_index, proto, source);
-    }
-
     if (0 == fib_table->ft_locks[FIB_TABLE_TOTAL_LOCKS])
     {
         /*