Trim spgist_private.h inclusion

It doesn't really need rel.h; relcache.h is enough.

src/backend/access/spgist/spgdoinsert.c

@@ -19,6 +19,7 @@
 #include "access/spgist_private.h"
 #include "miscadmin.h"
 #include "storage/bufmgr.h"
+#include "utils/rel.h"
 
 
 /*

src/backend/access/spgist/spginsert.c

@@ -24,6 +24,7 @@
 #include "storage/bufmgr.h"
 #include "storage/smgr.h"
 #include "utils/memutils.h"
+#include "utils/rel.h"
 
 
 typedef struct

src/backend/access/spgist/spgscan.c

@@ -21,6 +21,7 @@
 #include "storage/bufmgr.h"
 #include "utils/datum.h"
 #include "utils/memutils.h"
+#include "utils/rel.h"
 
 
 typedef void (*storeRes_func) (SpGistScanOpaque so, ItemPointer heapPtr,

src/include/access/spgist_private.h

@@ -17,7 +17,8 @@
 #include "access/itup.h"
 #include "access/spgist.h"
 #include "nodes/tidbitmap.h"
-#include "utils/rel.h"
+#include "storage/relfilenode.h"
+#include "utils/relcache.h"
 
 
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