misc/dist: fix file regexp
misc/dist: fix file regexp

This step makes it possible to upload the -osx10.x binaries
separately to their construction (after signing, for example).

R=golang-dev, dsymonds
CC=golang-dev
https://codereview.appspot.com/28160043

firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old