More optimization on LUNA frame buffer.
More optimization on LUNA frame buffer.

This is straightforward port of Izumi Tsutsui's work on NetBSD/luna68k:
http://mail-index.netbsd.org/source-changes/2014/09/28/msg058972.html

>> Put dumb optimizations to avoid conditionals in putchar drawing loops.

This makes 4bpp wscons putchar ~8% faster on luna88k.

ok miod@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars