gc: patch y.tab.c to fix build when using Bison 2.5
gc: patch y.tab.c to fix build when using Bison 2.5

Fixes issue 1843.

R=rsc
CC=golang-dev
http://codereview.appspot.com/4535101

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