Change rust library type back to `cdylib`

[stanislav-tkach]

Library type was changed to dylib as workaround for this problem: rust-lang/rust#39445.

Changed in #42.

[stanislav-tkach]

Probably should be fixed soon: https://github.com/Manishearth/rust-clippy/issues/1500.

[dmitry-timofeev]

Does it mean we can keep on living with cdylib? :-)

[stanislav-tkach]

Yes, although probably we can live with dylib too. 😄

[dmitry-timofeev]

It's up to you to decide which one is appropriate :-)