It uses SysV ABI too.

Disable '-D warnings` in CI to avoid `unexpected_cfgs` failures in a way
that doesn't break Rust 1.34.

This updates Fuchsia targets to print the `unknown` vendor, and adds
several more new targets.

Fixes #100.

Following the [logic in LLVM], make the binary format for most targets
be ELF instead of Unknown. To preserve round-tripping for Rust target
names, this requires some special-casing in the formatting code, but
this isn't new; a lot of targets require special cases to round-trip
properly.

[logic in LLVM]: https://github.com/llvm/llvm-project/blob/d3e7c4ce7a3d7f08cea02cba8f34c590a349688b/llvm/lib/TargetParser/Triple.cpp#L877

"pbc" = Pulley Bytecode. The 32 and 64 refer to the pointer size.

Add `pbc32` and `pbc64` architectures for Pulley

Bump to version v0.12.16

* Parse the deployment target on all Apple target triples

Also allow it to be optional, or partially specified.

* Add OperatingSystem::is_like_darwin

To more easily determine if the OS is of Darwin lineage.

* Define an ordering for DeploymentTarget

In the development of Pulley for Wasmtime we've realized that we're
going to need big-endian variants of Pulley in addition to
little-endian, so add that here.

Fixes #117.