reassembly: bug fixes

This change fixes a bug which would corrupt features infra by making
feature infra resistant to double-removal. It also fixes 'out of memory'
issue by properly initializing the bihash tables.

Change-Id: I78ac03139234a9a0e0b48e7bdfac1c38a0069e82
Signed-off-by: Klement Sekera <ksekera@cisco.com>
diff --git a/test/test_reassembly.py b/test/test_reassembly.py
index 531caa4..76aabcb 100644
--- a/test/test_reassembly.py
+++ b/test/test_reassembly.py
@@ -749,7 +749,6 @@
         self.assert_equal(icmp[ICMPv6ParamProblem].code, 0, "ICMP code")
 
 
-@unittest.skip("removing GRE tunnels broken, need fix")
 class TestFIFReassembly(VppTestCase):
     """ Fragments in fragments reassembly """
 
@@ -965,7 +964,7 @@
 
         # TODO remove gre vpp config by hand until VppIpRoute gets fixed
         # so that it's query_vpp_config() works as it should
-        # self.gre6.remove_vpp_config()
+        self.gre6.remove_vpp_config()
 
 
 if __name__ == '__main__':