Fixes #598. R=adg CC=golang-dev https://golang.org/cl/206089
(eliminate assumption of package global name space, make code easier to move between packages). R=r CC=golang-dev https://golang.org/cl/194072
* move memory code into $GOOS-specific directory. * allow printing of static strings < 256 bytes. (dynamic strings will bump maxstring as they are allocated.) * use cgo2c for runtime.mal. R=r, dho CC=golang-dev https://golang.org/cl/186143
R=rsc CC=golang-dev https://golang.org/cl/176066
