use new crate-type flag to build cdylib for android

[dvc94ch]

currently it causes cdylibs to be included on all platforms when it's set in Cargo.toml.

[MarijnS95]

@dvc94ch Do you think this is something we can insert manually? It can be passed as a flag to rustc which perhaps relieves some of the overhead of setting this in Cargo.toml manually.

I've also been wanting to figure this out (or find a workaround) for binaries so that you don't need to jump through hoops to make bin targets compatible on at least Android, and because a crate can have multiple bins but only a single lib.

[dvc94ch]

Yes. If it's a cdylib on all platforms, set it in Cargo.toml, on android add the crate-type cdylib

[MarijnS95]

@dvc94ch I ended up trying this out on cargo-apk and it seems to work, shall I port it to xbuild as well?

rust-mobile/cargo-apk#28

[MarijnS95]

Hmm, given the design of xbuild it seems to first call cargo build (which we'd have to replace by cargo rustc --crate-type ...), followed by platform-specific logic figuring out what would have been built, in order to collect the paths.

It supports a comma-separated list at least, so we'd have to list the build-requirements up-front...