Forgot to update cargo.lock before prior commit.

closes https://github.com/rust-lang/libc/issues/539

Also cache on appveyor to speed up builds.

in order to advise contributors to locally test their patches.

Also update ctest to include a fix on rerun-if-changed so that human
developers doing trial & error can properly test their latest code.

Signed-off-by: NODA, Kai <nodakai@gmail.com>

This commit adds support to test all libc definitions on both OpenBSD and
FreeBSD via QEMU userspace emulation. Specially prepared images for each OS are
used which are essentially intended to run a script on startup and then exit.
Documentation has been added to the `ci/README.md` file describing this new
system.

This should help the repo be resilient to ctest changes upstream.

Extracted tests!