Remove unused #include's from backend .c files

as determined by include-what-you-use (IWYU)

While IWYU also suggests to *add* a bunch of #include's (which is its
main purpose), this patch does not do that.  In some cases, a more
specific #include replaces another less specific one.

Some manual adjustments of the automatic result:

- IWYU currently doesn't know about includes that provide global
  variable declarations (like -Wmissing-variable-declarations), so
  those includes are being kept manually.

- All includes for port(ability) headers are being kept for now, to
  play it safe.

- No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the
  patch from exploding in size.

Note that this patch touches just *.c files, so nothing declared in
header files changes in hidden ways.

As a small example, in src/backend/access/transam/rmgr.c, some IWYU
pragma annotations are added to handle a special case there.

Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org

src/backend/rewrite/rewriteDefine.c

@@ -14,21 +14,15 @@
  */
 #include "postgres.h"
 
-#include "access/heapam.h"
 #include "access/htup_details.h"
-#include "access/multixact.h"
-#include "access/tableam.h"
-#include "access/transam.h"
-#include "access/xact.h"
+#include "access/relation.h"
+#include "access/table.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
-#include "catalog/heap.h"
+#include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
-#include "catalog/pg_inherits.h"
 #include "catalog/pg_rewrite.h"
-#include "catalog/storage.h"
-#include "commands/policy.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
 #include "parser/parse_utilcmd.h"
@@ -40,7 +34,6 @@
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
-#include "utils/snapmgr.h"
 #include "utils/syscache.h"
 
 

src/backend/rewrite/rewriteHandler.c

@@ -25,7 +25,6 @@
 #include "access/table.h"
 #include "catalog/dependency.h"
 #include "catalog/partition.h"
-#include "catalog/pg_type.h"
 #include "commands/trigger.h"
 #include "executor/executor.h"
 #include "foreign/fdwapi.h"

src/backend/rewrite/rewriteRemove.c

@@ -16,21 +16,15 @@
 
 #include "access/genam.h"
 #include "access/htup_details.h"
-#include "access/sysattr.h"
 #include "access/table.h"
 #include "catalog/catalog.h"
-#include "catalog/dependency.h"
 #include "catalog/indexing.h"
-#include "catalog/namespace.h"
 #include "catalog/pg_rewrite.h"
 #include "miscadmin.h"
 #include "rewrite/rewriteRemove.h"
-#include "utils/acl.h"
 #include "utils/fmgroids.h"
 #include "utils/inval.h"
-#include "utils/lsyscache.h"
 #include "utils/rel.h"
-#include "utils/syscache.h"
 
 /*
  * Guts of rule deletion.

src/backend/rewrite/rewriteSupport.c

@@ -17,12 +17,11 @@
 #include "access/htup_details.h"
 #include "access/table.h"
 #include "catalog/indexing.h"
+#include "catalog/pg_class.h"
 #include "catalog/pg_rewrite.h"
 #include "rewrite/rewriteSupport.h"
-#include "utils/fmgroids.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
-#include "utils/rel.h"
 #include "utils/syscache.h"
 
 

src/backend/rewrite/rowsecurity.c

@@ -34,30 +34,19 @@
  */
 #include "postgres.h"
 
-#include "access/htup_details.h"
-#include "access/sysattr.h"
 #include "access/table.h"
 #include "catalog/pg_class.h"
-#include "catalog/pg_inherits.h"
-#include "catalog/pg_policy.h"
 #include "catalog/pg_type.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
-#include "nodes/nodeFuncs.h"
 #include "nodes/pg_list.h"
-#include "nodes/plannodes.h"
-#include "parser/parsetree.h"
 #include "parser/parse_relation.h"
 #include "rewrite/rewriteDefine.h"
-#include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteManip.h"
 #include "rewrite/rowsecurity.h"
-#include "tcop/utility.h"
 #include "utils/acl.h"
-#include "utils/lsyscache.h"
 #include "utils/rel.h"
 #include "utils/rls.h"
-#include "utils/syscache.h"
 
 static void get_policies_for_relation(Relation relation,
 									  CmdType cmd, Oid user_id,