ssh/test: skip test on js/wasm
This should fix the build on the js/wasm builder.
Change-Id: I02a0ae00dcfd2691fbb4c7cf038b12988f3b4b85
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/172717
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>