test/float_lit2.go: fix constants for 386 platforms (fix build)
test/float_lit2.go: fix constants for 386 platforms (fix build)

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://codereview.appspot.com/95480045

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