Intialize DTM only when needed

Author: knizhnik

src/backend/storage/ipc/ipci.c

@@ -285,7 +285,6 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
 	 * Init array of Latches  in SHMEM for WAITLSN
 	 */
 	WaitLSNShmemInit();
-	DtmInitialize();
 
 	if (track_global_snapshots)
 		DtmInitialize();