* Make bootable doesn't complain when a boot-$arch script is missing if IGNORE_MISSING_BOOT_SCRIPT is set.

Makefile

@@ -554,9 +554,11 @@ $(BDIR)/bootable-stamp:
 		    echo "Running tools/boot/$(CODENAME)/boot-$(ARCH) $$n $$dir" ; \
 		    $(BASEDIR)/tools/boot/$(CODENAME)/boot-$(ARCH) $$n $$dir; \
 		else \
+		    if [ "$${IGNORE_MISSING_BOOT_SCRIPT:-0}" = "0" ]; then \
 			echo "No script to make CDs bootable for $(ARCH) ..."; \
 			exit 1; \
 		    fi; \
+		fi; \
 	done
 	$(Q)touch $(BDIR)/bootable-stamp