4.14.2 - Support compiling against Musl

What's Changed

Support compiling against Musl by @simonjbeaumont in #198

In order to compile this package against Musl libc, we need to not conflate #if os(Linux) with the ability to import Glibc. The common pattern for this is to use the #if canImport directive.

This patch adds support for Musl by replacing the Glibc import conditional alongside a new conditional import of Musl.

It also updates the linux_readpassphrase implementation to use the appropriate sigaction handler field for Musl.

This patch was released by @0xTim

Full Changelog: 4.14.1...4.14.2