Modify our boot block to pick an output device, without which boot1 will fail

on G4 machines. On the assumption that most people using FreeBSD on Apple
hardware are not using serial consoles, set boot1's output to screen. This
should be revisited. While here, reduce verbosity of boot1.

sys/boot/powerpc/boot1.chrp/boot1.c

@@ -561,6 +561,10 @@ printf(const char *fmt, ...)
 	va_list ap;
 	int ret;
 
+	/* Don't annoy the user as we probe for partitions */
+	if (strcmp(fmt,"Not ufs\n") == 0)
+		return 0;
+
 	va_start(ap, fmt);
 	ret = vprintf(fmt, ap);
 	va_end(ap);

sys/boot/powerpc/boot1.chrp/bootinfo.txt

@@ -7,6 +7,7 @@
 MacRISC MacRISC3 MacRISC4
 </COMPATIBLE>
 <BOOT-SCRIPT>
+" screen" output
 boot &device;:&partition;,\ppc\boot1.elf
 </BOOT-SCRIPT>
 </CHRP-BOOT>