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/misc/injection_point.c

@@ -17,6 +17,10 @@
  */
 #include "postgres.h"
 
+#include "utils/injection_point.h"
+
+#ifdef USE_INJECTION_POINTS
+
 #include <sys/stat.h>
 
 #include "fmgr.h"
@@ -25,11 +29,8 @@
 #include "storage/lwlock.h"
 #include "storage/shmem.h"
 #include "utils/hsearch.h"
-#include "utils/injection_point.h"
 #include "utils/memutils.h"
 
-#ifdef USE_INJECTION_POINTS
-
 /* Field sizes */
 #define INJ_NAME_MAXLEN		64
 #define INJ_LIB_MAXLEN		128

src/backend/utils/misc/pg_config.c

@@ -17,7 +17,6 @@
 #include "common/config_info.h"
 #include "funcapi.h"
 #include "miscadmin.h"
-#include "port.h"
 #include "utils/builtins.h"
 
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