Remove unused #include's from backend .c files

as determined by IWYU

These are mostly issues that are new since commit dbbca2cf29.

Discussion: https://www.postgresql.org/message-id/flat/0df1d5b1-8ca8-4f84-93be-121081bde049%40eisentraut.org

src/backend/utils/adt/float.c

@@ -27,7 +27,6 @@
 #include "utils/float.h"
 #include "utils/fmgrprotos.h"
 #include "utils/sortsupport.h"
-#include "utils/timestamp.h"
 
 
 /*

src/backend/utils/adt/jsonpath_exec.c

@@ -61,7 +61,6 @@
 
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
-#include "executor/execExpr.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "nodes/miscnodes.h"
@@ -74,7 +73,6 @@
 #include "utils/formatting.h"
 #include "utils/json.h"
 #include "utils/jsonpath.h"
-#include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/timestamp.h"
 

src/backend/utils/adt/pg_upgrade_support.c

@@ -28,7 +28,6 @@
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/pg_lsn.h"
-#include "utils/syscache.h"
 
 
 #define CHECK_IS_BINARY_UPGRADE									\

src/backend/utils/adt/waitfuncs.c

@@ -17,7 +17,7 @@
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/array.h"
-#include "utils/builtins.h"
+#include "utils/fmgrprotos.h"
 #include "utils/wait_event.h"
 
 #define UINT32_ACCESS_ONCE(var)		 ((uint32)(*((volatile uint32 *)&(var))))