Fix typos in commit 8586bf7ed8.

Author: Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1KNv1Mg2krf4E9ssWFnE=8A9mZ1VbVywXBZTFSzb+wP2g@mail.gmail.com

src/backend/access/table/tableamapi.c

@@ -103,9 +103,9 @@ get_table_am_oid(const char *tableamname, bool missing_ok)
 	ScanKeyData entry[1];
 
 	/*
-	 * Search pg_tablespace.  We use a heapscan here even though there is an
-	 * index on name, on the theory that pg_tablespace will usually have just
-	 * a few entries and so an indexed lookup is a waste of effort.
+	 * Search pg_am.  We use a heapscan here even though there is an index on
+	 * name, on the theory that pg_am will usually have just a few entries and
+	 * so an indexed lookup is a waste of effort.
 	 */
 	rel = heap_open(AccessMethodRelationId, AccessShareLock);
 

src/backend/utils/cache/relcache.c

@@ -1680,7 +1680,7 @@ InitTableAmRoutine(Relation relation)
 }
 
 /*
- * Initialize table access method support for a table like relation relation
+ * Initialize table access method support for a table like relation
  */
 void
 RelationInitTableAccessMethod(Relation relation)

src/include/access/tableam.h

@@ -4,7 +4,7 @@
  *	  POSTGRES table access method definitions.
  *
  *
- * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * src/include/access/tableam.h