This commit adds the wasm architecture to the time package.

Updates #18892

Change-Id: I86841e096894eacf7f972add9a532491e4d00014
Reviewed-on: https://go-review.googlesource.com/106997
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>