updated Arch dependencies, fixed gbm, mesa names

[feinedsquirrel]

As discussed on irc, the dependencies in the README.md could use a work over.

The Arch Linux declared dependencies are reduced, due to some being included as dependencies of others. I've submitted a comment to the AUR package to reflect these changes. You can see that comment here:
https://aur.archlinux.org/packages/wayvnc-git#comment-1048282

The full name for the libgbm and pkg-config as offered by dnf on fedora have prefixes that get auto-fixed when being installed. I've added the prefix to avoid confusion.

Finally, gbm.h on Ubuntu is offered in the libgbm-dev. It is an optional dep, but the end user can easily see what would be needed if they desire to have that functionality.

The Arch dependencies are tested and fully complete. I did not look deeper into the dnf and apt dependencies, and as such there may still be some corrections that can be made.

[any1]

Thanks. Git messages follow a certain pattern in this project. Did you read CONTRIBUTING.md? It's also a good idea to glance over the git log to get an idea of how things are supposed to look.

Debian/ubuntu users have it pretty easy because they can normally just run apt build-dep