Remove i386-specific hack for user register structure, made unnecessary by recent libgo update.
Remove i386-specific hack for user register structure, made
unnecessary by recent libgo update.

R=iant
https://golang.org/cl/2064041

qskycolor/gofrontend,golang/gofrontend,qskycolor/gofrontend,golang/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,golang/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,qskycolor/gofrontend,anlhord/gofrontend,golang/gofrontend,anlhord/gofrontend,anlhord/gofrontend,qskycolor/gofrontend