pg_dump: Allow pg_dump to dump the statistics for foreign tables.

Commit 1fd1bd8710 introduced support for dumping statistics with
pg_dump and pg_dumpall, covering tables, materialized views, and indexes.
However, it overlooked foreign tables, even though functions like
pg_restore_relation_stats() support them.

This commit fixes that oversight by allowing pg_dump and pg_dumpall
to include statistics for foreign tables.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/3772e4e4-ef39-4deb-bb76-aa8165f33fb6@oss.nttdata.com

doc/src/sgml/ref/pg_dump.sgml

@@ -1277,8 +1277,8 @@ PostgreSQL documentation
          </para>
          <para>
           The data section contains actual table data, large-object
-          contents, statistics for tables and materialized views and
-          sequence values.
+          contents, sequence values, and statistics for tables,
+          materialized views, and foriegn tables.
           Post-data items include definitions of indexes, triggers, rules,
           statistics for indexes, and constraints other than validated check
           constraints.
@@ -1359,7 +1359,8 @@ PostgreSQL documentation
       <listitem>
        <para>
         Dump only the statistics, not the schema (data definitions) or data.
-        Statistics for tables, materialized views, and indexes are dumped.
+        Statistics for tables, materialized views, foreign tables,
+        and indexes are dumped.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/ref/pg_dumpall.sgml

@@ -690,7 +690,8 @@ exclude database <replaceable class="parameter">PATTERN</replaceable>
       <listitem>
        <para>
         Dump only the statistics, not the schema (data definitions) or data.
-        Statistics for tables, materialized views, and indexes are dumped.
+        Statistics for tables, materialized views, foreign tables,
+        and indexes are dumped.
        </para>
       </listitem>
      </varlistentry>

src/bin/pg_dump/pg_dump.c

@@ -6890,7 +6890,8 @@ getRelationStatistics(Archive *fout, DumpableObject *rel, int32 relpages,
 		(relkind == RELKIND_PARTITIONED_TABLE) ||
 		(relkind == RELKIND_INDEX) ||
 		(relkind == RELKIND_PARTITIONED_INDEX) ||
-		(relkind == RELKIND_MATVIEW))
+		(relkind == RELKIND_MATVIEW ||
+		 relkind == RELKIND_FOREIGN_TABLE))
 	{
 		RelStatsInfo *info = pg_malloc0(sizeof(RelStatsInfo));
 		DumpableObject *dobj = &info->dobj;
@@ -6929,6 +6930,7 @@ getRelationStatistics(Archive *fout, DumpableObject *rel, int32 relpages,
 			case RELKIND_RELATION:
 			case RELKIND_PARTITIONED_TABLE:
 			case RELKIND_MATVIEW:
+			case RELKIND_FOREIGN_TABLE:
 				info->section = SECTION_DATA;
 				break;
 			case RELKIND_INDEX: