Looks like ubuntu 17.04 is broken now and it fails to link on 17.10 and 18.04.
It seems to work on stretch though!

Apparently 17.04 is broken now?

Looks like `cargo test` is now trying to test too many files due to
rust-lang/cargo#4750 so add a clause to the wrapper to ignore the bogus ones for
now

* Add syscall tables to most remaining arches in `src/unix/notbsd`
* Add aarch64/arm musl to CI
* Update dependencies

Signed-off-by: Tom Kirchner <tjk@amazon.com>
Signed-off-by: Ben Cressey <bcressey@amazon.com>

Apparently the 17.10 image broke?

Rebase of #610 and also move emscripten up much higher in the hierarchy to
ensure that it doesn't have too much of a ripple effect on other platforms.

This involved moving down a good number of definitions, but hopefully was done
with care to not break anything!

It's now broken due to changes in the `gcc` crate and having a too-old compiler,
and in general it's unfortunately architecturally so different from the other
test frameworks that it's difficult to maintain over time.

We can't test s390x because qemu segfaults but we can at least verify that it
compiles.

Closes #650

This helps caching between runs and can help speed up turnaround time for
various operations. The old android container didn't work out for some reason
due to permissions so the definition has now been vendored locally to just
rebuild it each time.

Also cache on appveyor to speed up builds.

* Override the compiler via CC; ./configure can't seem to detect it.
* Unset CROSS_COMPILE when running make. Per the comment, we otherwise
  end up invoking commands like i686-ar.

Specifically:

* Update the base docker images to ubuntu 16.10
* Update musl to version 1.1.15

This is necessary since the versions we were previously using do not
define CLONE_NEWCGROUP, so adding the symbol to the libc crate causes
test failures.

and fix the statvfs struct for this target