internal/goos: fix bug in gengoos.go
CL 601357 mistakenly added an extra period.
Change-Id: I54db621663797f094059a4eb86bf5d9626fa59d6
GitHub-Last-Rev:
c756e0a82427c44b00bd88547dc40bf88c85fc1f
GitHub-Pull-Request: golang/go#70733
Reviewed-on: https://go-review.googlesource.com/c/go/+/634517
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>