cmd/toolstash: don't build cmd for android

Linking cmd for android requires a cross-compiling toolchain,
which is not standard fare.

Skip it, and trust that the other platforms will pick up the slack.

Change-Id: Ifcf74f77e98489c859805ab7a448d80d019f3d20
Reviewed-on: https://go-review.googlesource.com/39556
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/toolstash/buildall

diff --git a/cmd/toolstash/buildall b/cmd/toolstash/buildall
index d8ec221..40d88f5 100755
--- a/cmd/toolstash/buildall
+++ b/cmd/toolstash/buildall
@@ -57,7 +57,11 @@
 		export GO386=387
 	fi
 	if $cmp; then
-		go build $work -a -toolexec 'toolstash -cmp' std cmd
+		if [ "$GOOS" = "android" ]; then
+			go build $work -a -toolexec 'toolstash -cmp' std
+		else
+			go build $work -a -toolexec 'toolstash -cmp' std cmd
+		fi
 	else
 		go build $work -a std
 	fi