test: add test for gccgo comment lexing failure
test: add test for gccgo comment lexing failure

http://gcc.gnu.org/PR61746

http://code.google.com/p/gofrontend/issues/detail?id=35

LGTM=crawshaw
R=golang-codereviews, crawshaw
CC=golang-codereviews
https://codereview.appspot.com/111980043

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