go/version: fix package to accept go1.21.0-bigcorp
The proposal discussion made clear that suffixes should be accepted,
so that people who use custom VERSION files can still pass runtime.Version()
to this code. But we forgot to do that in the CL. Do that.
Note that cmd/go also strips space- and tab-prefixed suffixes,
but go.dev/doc/toolchain only mentions dash, so this code only
strips dash.
Fixes #65061.
Change-Id: I6a427b78f964eb41c024890dae30223beaef13eb
Cq-Include-Trybots: luci.golang.try:gotip-linux-amd64-longtest,gotip-windows-amd64-longtest
Reviewed-on: https://go-review.googlesource.com/c/go/+/559796
TryBot-Bypass: Russ Cox <rsc@golang.org> Reviewed-by: Mauri de Souza Meneguzzo <mauri870@gmail.com> Reviewed-by: Bryan Mills <bcmills@google.com>