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/access/heap/heapam.c

@@ -32,7 +32,6 @@
 #include "postgres.h"
 
 #include "access/bufmask.h"
-#include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
 #include "access/heaptoast.h"
@@ -62,12 +61,9 @@
 #include "storage/lmgr.h"
 #include "storage/predicate.h"
 #include "storage/procarray.h"
-#include "storage/smgr.h"
-#include "storage/spin.h"
 #include "storage/standby.h"
 #include "utils/datum.h"
 #include "utils/inval.h"
-#include "utils/lsyscache.h"
 #include "utils/relcache.h"
 #include "utils/snapmgr.h"
 #include "utils/spccache.h"

src/backend/access/heap/heapam_visibility.c

@@ -69,7 +69,6 @@
 #include "access/heapam.h"
 #include "access/htup_details.h"
 #include "access/multixact.h"
-#include "access/subtrans.h"
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
@@ -77,7 +76,6 @@
 #include "storage/bufmgr.h"
 #include "storage/procarray.h"
 #include "utils/builtins.h"
-#include "utils/combocid.h"
 #include "utils/snapmgr.h"
 
 

src/backend/access/heap/hio.c

@@ -22,7 +22,6 @@
 #include "storage/bufmgr.h"
 #include "storage/freespace.h"
 #include "storage/lmgr.h"
-#include "storage/smgr.h"
 
 
 /*

src/backend/access/heap/pruneheap.c

@@ -20,13 +20,11 @@
 #include "access/transam.h"
 #include "access/xlog.h"
 #include "access/xloginsert.h"
-#include "catalog/catalog.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
 #include "utils/snapmgr.h"
 #include "utils/rel.h"
-#include "utils/snapmgr.h"
 
 /* Working data for heap_page_prune and subroutines */
 typedef struct

src/backend/access/heap/rewriteheap.c

@@ -111,12 +111,10 @@
 #include "access/transam.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
-#include "catalog/catalog.h"
 #include "common/file_utils.h"
 #include "lib/ilist.h"
 #include "miscadmin.h"
 #include "pgstat.h"
-#include "replication/logical.h"
 #include "replication/slot.h"
 #include "storage/bufmgr.h"
 #include "storage/bulk_write.h"

src/backend/access/heap/vacuumlazy.c

@@ -34,7 +34,6 @@
 
 #include <math.h>
 
-#include "access/amapi.h"
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
@@ -42,24 +41,19 @@
 #include "access/multixact.h"
 #include "access/transam.h"
 #include "access/visibilitymap.h"
-#include "access/xact.h"
-#include "access/xlog.h"
 #include "access/xloginsert.h"
-#include "catalog/index.h"
 #include "catalog/storage.h"
 #include "commands/dbcommands.h"
 #include "commands/progress.h"
 #include "commands/vacuum.h"
 #include "executor/instrument.h"
 #include "miscadmin.h"
-#include "optimizer/paths.h"
 #include "pgstat.h"
 #include "portability/instr_time.h"
 #include "postmaster/autovacuum.h"
 #include "storage/bufmgr.h"
 #include "storage/freespace.h"
 #include "storage/lmgr.h"
-#include "tcop/tcopprot.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/pg_rusage.h"

src/backend/access/heap/visibilitymap.c

@@ -93,9 +93,9 @@
 #include "miscadmin.h"
 #include "port/pg_bitutils.h"
 #include "storage/bufmgr.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/inval.h"
+#include "utils/rel.h"
 
 
 /*#define TRACE_VISIBILITYMAP */