openflow_input: add of_oxm_bsn_in_ports_512

This requires support from the backends for the new datatype.
diff --git a/test_data/of13/oxm_bsn_in_ports_masked_512.data b/test_data/of13/oxm_bsn_in_ports_masked_512.data
new file mode 100644
index 0000000..82cc45c
--- /dev/null
+++ b/test_data/of13/oxm_bsn_in_ports_masked_512.data
@@ -0,0 +1,36 @@
+-- binary
+00 03 # class
+27 # type/masked
+80 # length
+00 00 00 00 00 00 00 00 # value
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+00 00 00 00 00 00 00 00 # ...
+7f ff ff ff ff ff ff ff # mask - Only ports 0, 17, 96, 511 are selected (and thus are zero)
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff ff ff ff ff ff # ...
+ff ff ff fe ff ff ff ff # ...
+ff ff ff ff ff fd ff fe # ...
+-- python
+ofp.oxm.bsn_in_ports_512_masked(set(), set(range(0,512)) - set((0, 17, 96, 511)))
+-- c
+obj = of_oxm_bsn_in_ports_512_masked_new(OF_VERSION_1_3);
+{
+    of_bitmap_512_t bmap = { { 0, 0, 0, 0, 0, 0, 0, 0 } };
+    of_oxm_bsn_in_ports_512_masked_value_set(obj, bmap);
+}
+{
+    of_bitmap_512_t bmap = { { 0x7fffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff, 0xfffffffeffffffff, 0xfffffffffffdfffe } };
+    of_oxm_bsn_in_ports_512_masked_value_mask_set(obj, bmap);
+}
+-- java
+OFPortMap portmap = OFPortMap.ofPorts(OFPort.of(0), OFPort.of(17), OFPort.of(96));
+builder.setValue(portmap.getValue());
+builder.setMask(portmap.getMask());