Remove unreferenced pg_opfamily entry.

The entry with OID 4035, for GIST jsonb_ops, is unused; apparently
it was added in preparation for index support that never materialized.
Remove it, and add a regression test case to detect future mistakes
of the same kind.

Discussion: https://postgr.es/m/17188.1541379745@sss.pgh.pa.us

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201811012
+#define CATALOG_VERSION_NO	201811051
 
 #endif

src/include/catalog/pg_opfamily.dat

@@ -172,8 +172,6 @@
   opfmethod => 'btree', opfname => 'jsonb_ops' },
 { oid => '4034',
   opfmethod => 'hash', opfname => 'jsonb_ops' },
-{ oid => '4035',
-  opfmethod => 'gist', opfname => 'jsonb_ops' },
 { oid => '4036',
   opfmethod => 'gin', opfname => 'jsonb_ops' },
 { oid => '4037',

src/test/regress/expected/opr_sanity.out

@@ -1686,6 +1686,16 @@ WHERE p1.opfmethod = 0 OR p1.opfnamespace = 0;
 -----
 (0 rows)
 
+-- Look for opfamilies having no opclasses.  While most validation of
+-- opfamilies is now handled by AM-specific amvalidate functions, that's
+-- driven from pg_opclass entries below, so an empty opfamily would not
+-- get noticed.
+SELECT oid, opfname FROM pg_opfamily f
+WHERE NOT EXISTS (SELECT 1 FROM pg_opclass WHERE opcfamily = f.oid);
+ oid | opfname 
+-----+---------
+(0 rows)
+
 -- **************** pg_opclass ****************
 -- Look for illegal values in pg_opclass fields
 SELECT p1.oid

src/test/regress/sql/opr_sanity.sql

@@ -1122,6 +1122,14 @@ SELECT p1.oid
 FROM pg_opfamily as p1
 WHERE p1.opfmethod = 0 OR p1.opfnamespace = 0;
 
+-- Look for opfamilies having no opclasses.  While most validation of
+-- opfamilies is now handled by AM-specific amvalidate functions, that's
+-- driven from pg_opclass entries below, so an empty opfamily would not
+-- get noticed.
+
+SELECT oid, opfname FROM pg_opfamily f
+WHERE NOT EXISTS (SELECT 1 FROM pg_opclass WHERE opcfamily = f.oid);
+
 
 -- **************** pg_opclass ****************