all: fix buildall.bash

all: fix buildall.bash

Disable the android and ios builds since cross-compiling fails there.
Also make runtime/internal/wasitest not build on systems that don't
have syscall.Mkfifo for it to use (including, ironically, wasm itself).

Change-Id: I28eb1f216f9952f81a107056e97ee38e350f9287
Reviewed-on: https://go-review.googlesource.com/c/go/+/498255
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>