C includes: Reorder C includes in partition.c

Discussion: https://postgr.es/m/5A69AA50.2060600@lab.ntt.co.jp

Author: Etsuro Fujita

src/backend/catalog/partition.c

@@ -46,11 +46,11 @@
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
-#include "utils/memutils.h"
 #include "utils/fmgroids.h"
 #include "utils/hashutils.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
+#include "utils/memutils.h"
 #include "utils/rel.h"
 #include "utils/ruleutils.h"
 #include "utils/syscache.h"