image/jpeg: ignore an incorrect but harmless trailing restart marker.
image/jpeg: ignore an incorrect but harmless trailing restart marker.

Fixes issue 4084.

R=r
CC=golang-dev
http://codereview.appspot.com/6526043
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go