Remove unused function.

The code in InitPostgres() was refactored in PostgreSQL 9.0 so that it
no longer uses FindMyDatabaseByOid() function. We had backpatched the
InitPostgres() changes already, so backpatch the removal of
FindMyDatabaseByOid() as well. Silences a compiler warning.

src/backend/utils/init/postinit.c

@@ -315,48 +315,6 @@ ProcessRoleGUC(void)
 	caql_endscan(pcqCtx);
 }
 
-/*
- * FindMyDatabaseByOid
- *
- * As above, but the actual database Id is known.  Return its name and the 
- * tablespace OID.  Return TRUE if found, FALSE if not.  The same restrictions
- * as FindMyDatabase apply.
- */
-static bool
-FindMyDatabaseByOid(Oid dbid, char *dbname, Oid *db_tablespace)
-{
-	bool		result = false;
-	char	   *filename;
-	FILE	   *db_file;
-	Oid			db_id;
-	char		thisname[NAMEDATALEN];
-	TransactionId db_frozenxid;
-
-	filename = database_getflatfilename();
-	db_file = AllocateFile(filename, "r");
-	if (db_file == NULL)
-		ereport(FATAL,
-				(errcode_for_file_access(),
-				 errmsg("could not open file \"%s\": %m", filename)));
-
-	while (read_pg_database_line(db_file, thisname, &db_id,
-								 db_tablespace, &db_frozenxid))
-	{
-		if (dbid == db_id)
-		{
-			result = true;
-			strlcpy(dbname, thisname, NAMEDATALEN);
-			break;
-		}
-	}
-
-	FreeFile(db_file);
-	pfree(filename);
-
-	return result;
-}
-
-
 /*
  * CheckMyDatabase -- fetch information from the pg_database entry for our DB
  */