postgres_fdw: Reorder C includes.

Reorder header files in postgres_fdw.c and connection.c in alphabetical
order.

Author: Etsuro Fujita
Reviewed-by: Alvaro Herrera
Discussion: https://postgr.es/m/CAPmGK17ZmNb-EELqu8LmMh2t2uFdbfWNVDEfDO5-bpejHPONMQ@mail.gmail.com

contrib/postgres_fdw/connection.c

@@ -15,8 +15,8 @@
 #include "postgres_fdw.h"
 
 #include "access/htup_details.h"
-#include "catalog/pg_user_mapping.h"
 #include "access/xact.h"
+#include "catalog/pg_user_mapping.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "pgstat.h"

contrib/postgres_fdw/postgres_fdw.c

@@ -26,8 +26,8 @@
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
-#include "optimizer/cost.h"
 #include "optimizer/clauses.h"
+#include "optimizer/cost.h"
 #include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"