[client] wayland: Use full buffer for wayland viewport source

[kamplom]

Prevents the client from crashing when using factorial scaling in Wayland. See libsdl-org/SDL#9283 (comment) for technical explanation.
Fixes #1113. Tested with hyprland and plasma on wayland.

[gnif]

Thanks but you need to make a few changes.

1. This project has adopted an 80 column width limit, please adjust your patch to conform to this.
2. Please add yourself to the AUTHORS file as a requirement of contributing.
3. Please adjust the commit format to conform with the project, in this case it should read [client] wayland: ...

[gnif]

I am sorry, while you have made the requested changes it has been done improperly.

1. Please squash your changes into a single commit (hint: git rebase -i)
2. Please adjust the comment message of your changes, not the title of this issue (hint: git commit --amend)

As this is a fork of the project you can force push to it (git push -f) which will update this PR accordingly

[kamplom]

Should be OK now. Thanks for taking your time to explain the proper way to do it, and sorry for the inconvenience