build: improve the Linux aspect of things

[Tachi107]

This is still a work in progress, and is likely going to conflict with #9 (Cc: @Zopolis4)

With this PR I aim at making Cemu's build script more compatible with how Linux operates, so this mainly means that system dependencies will be used when possible.

I'll split the changes in different commits on purpose, so please don't squash this on merge.

Could potentially fix #1.

Blockers: https://github.com/Exzap/ZArchive/pull/7