Further cleanup of client dependencies on src/include/catalog headers.

In commit 9c0a0de4, I'd failed to notice that catalog/catalog.h
should also be considered a frontend-unsafe header, because it includes
(and needs) the full form of pg_class.h, not to mention relcache.h.
However, various frontend code was depending on it to get
TABLESPACE_VERSION_DIRECTORY, so refactoring of some sort is called for.

The cleanest answer seems to be to move TABLESPACE_VERSION_DIRECTORY,
as well as the OIDCHARS symbol, to common/relpath.h.  Do that, and mop up
inclusions as necessary.  (I found that quite a few current users of
catalog/catalog.h don't seem to need it at all anymore, apparently as a
result of the refactorings that created common/relpath.[hc].  And
initdb.c needed it only as a route to pg_class_d.h.)

Discussion: https://postgr.es/m/6629.1523294509@sss.pgh.pa.us

contrib/pageinspect/rawpage.c

@@ -18,7 +18,6 @@
 #include "pageinspect.h"
 
 #include "access/htup_details.h"
-#include "catalog/catalog.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"

contrib/pg_prewarm/pg_prewarm.c

@@ -16,7 +16,6 @@
 #include <unistd.h>
 
 #include "access/heapam.h"
-#include "catalog/catalog.h"
 #include "fmgr.h"
 #include "miscadmin.h"
 #include "storage/bufmgr.h"

src/backend/access/index/indexam.c

@@ -73,7 +73,6 @@
 #include "access/relscan.h"
 #include "access/transam.h"
 #include "access/xlog.h"
-#include "catalog/catalog.h"
 #include "catalog/index.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"

src/backend/access/rmgrdesc/smgrdesc.c

@@ -14,7 +14,6 @@
  */
 #include "postgres.h"
 
-#include "catalog/catalog.h"
 #include "catalog/storage_xlog.h"
 
 

src/backend/access/rmgrdesc/xactdesc.c

@@ -16,7 +16,6 @@
 
 #include "access/transam.h"
 #include "access/xact.h"
-#include "catalog/catalog.h"
 #include "storage/sinval.h"
 #include "storage/standbydefs.h"
 #include "utils/timestamp.h"

src/backend/access/transam/xact.c

@@ -30,7 +30,6 @@
 #include "access/xlog.h"
 #include "access/xloginsert.h"
 #include "access/xlogutils.h"
-#include "catalog/catalog.h"
 #include "catalog/namespace.h"
 #include "catalog/storage.h"
 #include "commands/async.h"

src/backend/access/transam/xlogfuncs.c

@@ -20,7 +20,6 @@
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogutils.h"
-#include "catalog/catalog.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"

src/backend/access/transam/xlogutils.c

@@ -23,7 +23,6 @@
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xlogutils.h"
-#include "catalog/catalog.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/smgr.h"

src/backend/catalog/storage.c

@@ -24,7 +24,6 @@
 #include "access/xlog.h"
 #include "access/xloginsert.h"
 #include "access/xlogutils.h"
-#include "catalog/catalog.h"
 #include "catalog/storage.h"
 #include "catalog/storage_xlog.h"
 #include "storage/freespace.h"

src/backend/commands/vacuumlazy.c

@@ -44,7 +44,6 @@
 #include "access/transam.h"
 #include "access/visibilitymap.h"
 #include "access/xlog.h"
-#include "catalog/catalog.h"
 #include "catalog/storage.h"
 #include "commands/dbcommands.h"
 #include "commands/progress.h"

src/backend/replication/basebackup.c

@@ -17,7 +17,6 @@
 #include <time.h>
 
 #include "access/xlog_internal.h"	/* for pg_start/stop_backup */
-#include "catalog/catalog.h"
 #include "catalog/pg_type.h"
 #include "common/file_perm.h"
 #include "lib/stringinfo.h"

src/backend/storage/file/fd.c

@@ -82,7 +82,6 @@
 #include "miscadmin.h"
 #include "access/xact.h"
 #include "access/xlog.h"
-#include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
 #include "common/file_perm.h"
 #include "pgstat.h"

src/backend/storage/file/reinit.c

@@ -16,7 +16,6 @@
 
 #include <unistd.h>
 
-#include "catalog/catalog.h"
 #include "common/relpath.h"
 #include "storage/copydir.h"
 #include "storage/fd.h"

src/backend/storage/smgr/md.c

@@ -27,7 +27,6 @@
 
 #include "miscadmin.h"
 #include "access/xlog.h"
-#include "catalog/catalog.h"
 #include "pgstat.h"
 #include "portability/instr_time.h"
 #include "postmaster/bgwriter.h"

src/bin/initdb/initdb.c

@@ -60,8 +60,8 @@
 #endif
 
 #include "access/xlog_internal.h"
-#include "catalog/catalog.h"
 #include "catalog/pg_authid_d.h"
+#include "catalog/pg_class_d.h" /* pgrminclude ignore */
 #include "catalog/pg_collation_d.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"

src/bin/pg_rewind/copy_fetch.c

@@ -21,8 +21,6 @@
 #include "logging.h"
 #include "pg_rewind.h"
 
-#include "catalog/catalog.h"
-
 static void recurse_dir(const char *datadir, const char *path,
 			process_file_callback_t callback);
 

src/bin/pg_rewind/filemap.c

@@ -19,7 +19,6 @@
 #include "pg_rewind.h"
 
 #include "common/string.h"
-#include "catalog/catalog.h"
 #include "catalog/pg_tablespace_d.h"
 #include "storage/fd.h"
 

src/bin/pg_rewind/libpq_fetch.c

@@ -22,7 +22,6 @@
 #include "logging.h"
 
 #include "libpq-fe.h"
-#include "catalog/catalog.h"
 #include "catalog/pg_type_d.h"
 #include "fe_utils/connect.h"
 #include "port/pg_bswap.h"

src/common/relpath.c

@@ -18,7 +18,6 @@
 #include "postgres_fe.h"
 #endif
 
-#include "catalog/catalog.h"
 #include "catalog/pg_tablespace_d.h"
 #include "common/relpath.h"
 #include "storage/backendid.h"

src/include/catalog/catalog.h

@@ -14,18 +14,9 @@
 #ifndef CATALOG_H
 #define CATALOG_H
 
-/*
- *	'pgrminclude ignore' needed here because CppAsString2() does not throw
- *	an error if the symbol is not defined.
- */
-#include "catalog/catversion.h" /* pgrminclude ignore */
 #include "catalog/pg_class.h"
 #include "utils/relcache.h"
 
-#define OIDCHARS		10		/* max chars printed by %u */
-#define TABLESPACE_VERSION_DIRECTORY	"PG_" PG_MAJORVERSION "_" \
-									CppAsString2(CATALOG_VERSION_NO)
-
 
 extern bool IsSystemRelation(Relation relation);
 extern bool IsToastRelation(Relation relation);

src/include/common/relpath.h

@@ -13,6 +13,22 @@
 #ifndef RELPATH_H
 #define RELPATH_H
 
+/*
+ *	'pgrminclude ignore' needed here because CppAsString2() does not throw
+ *	an error if the symbol is not defined.
+ */
+#include "catalog/catversion.h" /* pgrminclude ignore */
+
+
+/*
+ * Name of major-version-specific tablespace subdirectories
+ */
+#define TABLESPACE_VERSION_DIRECTORY	"PG_" PG_MAJORVERSION "_" \
+									CppAsString2(CATALOG_VERSION_NO)
+
+/* Characters to allow for an OID in a relation path */
+#define OIDCHARS		10		/* max chars printed by %u */
+
 /*
  * Stuff for fork names.
  *