Add NES emulator

It's now possible to play classic video game roms with teletypewriters.
https://justine.storage.googleapis.com/nesemu.png

libc/libc.mk

@@ -26,6 +26,7 @@ o/$(MODE)/libc:	o/$(MODE)/libc/alg		\
 		o/$(MODE)/libc/math		\
 		o/$(MODE)/libc/mem		\
 		o/$(MODE)/libc/nexgen32e	\
+		o/$(MODE)/libc/ohmyplus		\
 		o/$(MODE)/libc/rand		\
 		o/$(MODE)/libc/runtime		\
 		o/$(MODE)/libc/sock		\