4.99.2 - Support compiling against Musl

What's Changed

Support compiling against Musl by @simonjbeaumont in #3188

Vapor already makes some provision for compiling against Musl in the RFC1123 implementation, where Glibc is not assumed and is imported conditionally alongside a conditional import of Musl. However, there are a couple of other places where Glibc is still assumed when compiling for Linux.

This patch replaces these imports with the same #if canImport(...) pattern.

This patch was released by @0xTim

Full Changelog: 4.99.1...4.99.2