Create an SP-GiST opclass for inet/cidr.

This seems to offer significantly better search performance than the
existing GiST opclass for inet/cidr, at least on data with a wide mix
of network mask lengths.  (That may suggest that the data splitting
heuristics in the GiST opclass could be improved.)

Emre Hasegeli, with mostly-cosmetic adjustments by me

Discussion: <CAE2gYzxtth9qatW_OAqdOjykS0bxq7AYHLuyAQLPgT7H9ZU0Cw@mail.gmail.com>

Author: tglsfdc

doc/src/sgml/spgist.sgml

@@ -145,6 +145,23 @@
        <literal>~&gt;~</>
       </entry>
      </row>
+     <row>
+      <entry><literal>inet_ops</></entry>
+      <entry><type>inet</>, <type>cidr</></entry>
+      <entry>
+       <literal>&amp;&amp;</>
+       <literal>&gt;&gt;</>
+       <literal>&gt;&gt;=</>
+       <literal>&gt;</>
+       <literal>&gt;=</>
+       <literal>&lt;&gt;</>
+       <literal>&lt;&lt;</>
+       <literal>&lt;&lt;=</>
+       <literal>&lt;</>
+       <literal>&lt;=</>
+       <literal>=</>
+      </entry>
+     </row>
     </tbody>
    </tgroup>
   </table>

src/backend/utils/adt/Makefile

@@ -17,7 +17,7 @@ OBJS = acl.o amutils.o arrayfuncs.o array_expanded.o array_selfuncs.o \
 	geo_ops.o geo_selfuncs.o geo_spgist.o inet_cidr_ntop.o inet_net_pton.o \
 	int.o int8.o json.o jsonb.o jsonb_gin.o jsonb_op.o jsonb_util.o \
 	jsonfuncs.o like.o lockfuncs.o mac.o misc.o nabstime.o name.o \
-	network.o network_gist.o network_selfuncs.o \
+	network.o network_gist.o network_selfuncs.o network_spgist.o \
 	numeric.o numutils.o oid.o oracle_compat.o \
 	orderedsetaggs.o pg_locale.o pg_lsn.o pg_upgrade_support.o \
 	pgstatfuncs.o \