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/tsearch/dict.c

@@ -15,7 +15,7 @@
 
 #include "catalog/pg_type.h"
 #include "tsearch/ts_cache.h"
-#include "tsearch/ts_utils.h"
+#include "tsearch/ts_public.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
 

src/backend/tsearch/dict_ispell.c

@@ -16,8 +16,8 @@
 #include "commands/defrem.h"
 #include "tsearch/dicts/spell.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_utils.h"
-#include "utils/builtins.h"
+#include "tsearch/ts_public.h"
+#include "utils/fmgrprotos.h"
 
 
 typedef struct

src/backend/tsearch/dict_simple.c

@@ -15,8 +15,8 @@
 
 #include "commands/defrem.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_utils.h"
-#include "utils/builtins.h"
+#include "tsearch/ts_public.h"
+#include "utils/fmgrprotos.h"
 
 
 typedef struct

src/backend/tsearch/dict_synonym.c

@@ -15,8 +15,8 @@
 
 #include "commands/defrem.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_utils.h"
-#include "utils/builtins.h"
+#include "tsearch/ts_public.h"
+#include "utils/fmgrprotos.h"
 
 typedef struct
 {

src/backend/tsearch/dict_thesaurus.c

@@ -17,8 +17,8 @@
 #include "commands/defrem.h"
 #include "tsearch/ts_cache.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_utils.h"
-#include "utils/builtins.h"
+#include "tsearch/ts_public.h"
+#include "utils/fmgrprotos.h"
 #include "utils/regproc.h"
 
 

src/backend/tsearch/to_tsany.c

@@ -13,7 +13,6 @@
  */
 #include "postgres.h"
 
-#include "common/jsonapi.h"
 #include "tsearch/ts_cache.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"

src/backend/tsearch/ts_locale.c

@@ -13,11 +13,9 @@
  */
 #include "postgres.h"
 
-#include "catalog/pg_collation.h"
 #include "common/string.h"
 #include "storage/fd.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_public.h"
 
 static void tsearch_readline_callback(void *arg);
 

src/backend/tsearch/ts_selfuncs.c

@@ -19,10 +19,9 @@
 #include "miscadmin.h"
 #include "nodes/nodes.h"
 #include "tsearch/ts_type.h"
-#include "utils/builtins.h"
+#include "utils/fmgrprotos.h"
 #include "utils/lsyscache.h"
 #include "utils/selfuncs.h"
-#include "utils/syscache.h"
 
 
 /*

src/backend/tsearch/ts_utils.c

@@ -18,7 +18,7 @@
 
 #include "miscadmin.h"
 #include "tsearch/ts_locale.h"
-#include "tsearch/ts_utils.h"
+#include "tsearch/ts_public.h"
 
 
 /*

src/backend/tsearch/wparser.c

@@ -14,13 +14,11 @@
 #include "postgres.h"
 
 #include "catalog/namespace.h"
-#include "catalog/pg_type.h"
 #include "commands/defrem.h"
-#include "common/jsonapi.h"
 #include "funcapi.h"
 #include "tsearch/ts_cache.h"
 #include "tsearch/ts_utils.h"
-#include "utils/builtins.h"
+#include "utils/fmgrprotos.h"
 #include "utils/jsonfuncs.h"
 #include "utils/varlena.h"
 

src/backend/tsearch/wparser_def.c

@@ -15,15 +15,16 @@
 #include "postgres.h"
 
 #include <limits.h>
+#include <wctype.h>
 
-#include "catalog/pg_collation.h"
 #include "commands/defrem.h"
+#include "mb/pg_wchar.h"
 #include "miscadmin.h"
-#include "tsearch/ts_locale.h"
 #include "tsearch/ts_public.h"
 #include "tsearch/ts_type.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 
 /* Define me to enable tracing of parser behavior */