try disconnecting old world boot.mac bootloader for a bit

src/etc/etc.macppc/Makefile.inc

@@ -1,10 +1,9 @@
-#	$OpenBSD: Makefile.inc,v 1.17 2017/04/04 00:03:12 deraadt Exp $
+#	$OpenBSD: Makefile.inc,v 1.18 2020/01/26 04:26:46 tedu Exp $
 
 KERNELS += GENERIC.MP bsd.mp
 
 bootblocks:
 	cp -p ${DESTDIR}/usr/mdec/ofwboot ${RELEASEDIR}/ofwboot
 	cp -p ${DESTDIR}/usr/mdec/bsd.tbxi ${RELEASEDIR}/bsd.tbxi
-	cp -p ${DESTDIR}/usr/mdec/boot.mac ${RELEASEDIR}/boot.mac
 
-MDEXT=	bsd.rd cd${OSrev}.iso ofwboot bsd.tbxi boot.mac
+MDEXT=	bsd.rd cd${OSrev}.iso ofwboot bsd.tbxi