androidtest.bash: don't require GOARCH set
androidtest.bash: don't require GOARCH set

The host GOARCH is most likely supported (386, amd64, arm, arm64).

Change-Id: I86324b9c00f22c592ba54bda7d2ae97c86bda904
Reviewed-on: https://go-review.googlesource.com/99155
Run-TryBot: Elias Naur <993af7099cb24ce1a88d64108ae1e8b0385f2fc0@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <d7e82c3c07f92613bcbf9a1e88f6b96c13caa3b0@gmail.com>

akutz/go,Cofyc/go,CAFxX/go,josharian/go,akutz/go,codestation/go,josharian/go,codestation/go,golang/go,nawawi/go,akutz/go,codestation/go,cloudflare/go,cloudflare/go,golang/go,codestation/go,golang/go,Cofyc/go,nawawi/go,akutz/go,josharian/go,CAFxX/go,akutz/go,CAFxX/go,nawawi/go,Cofyc/go,nawawi/go,golang/go,nawawi/go,cloudflare/go,Cofyc/go,CAFxX/go,nawawi/go,akutz/go,cloudflare/go,CAFxX/go,josharian/go,akutz/go,golang/go,nawawi/go,cloudflare/go,josharian/go,cloudflare/go,golang/go,codestation/go,cloudflare/go,golang/go,Cofyc/go,josharian/go,josharian/go,akutz/go,codestation/go,CAFxX/go,golang/go,codestation/go,CAFxX/go,Cofyc/go,nawawi/go,josharian/go,cloudflare/go,Cofyc/go,CAFxX/go,Cofyc/go,codestation/go