Remove X11 as a default feature

[james7132]

Objective

Follow-up to #19232. X11 support is on the downturn, with other players like GTK announcing that they're considering deprecating X11 support in the next major release and Fedora 43 later this year is going to be Wayland only.

Solution

Remove x11 as a default feature from the top level bevy crate.

Testing

Local build run of 3d_example. This doesn't seem to impact compile times significantly. Release builds shave off about 1MB.

[github-actions]

It looks like your PR is a breaking change, but you didn't provide a migration guide.

Please review the instructions for writing migration guides, then expand or revise the content in the migration guides directory to reflect your changes.

[hukasu]

update this comment

bevy/crates/bevy_internal/Cargo.toml

Lines 138 to 140 in 4cf5fc3

	# Display server protocol support (X11 is enabled by default)
	wayland = ["bevy_winit/wayland"]
	x11 = ["bevy_winit/x11"]

[cart]

This feels a bit premature. If we do this now we're close to being a "first mover". Id prefer to not trade platform support for leanness in this particular case / at this phase of the x11 deprecation. Linux is already a compatibility nightmare. I see no reason to cut out a percentage of users by default.

[james7132]

Looking deeper into it, it seems like they're just dropping the X session, and not the headers. Right now it seems like it's only KDE and GNOME that have made the jump and Cosmic that was built natively in Wayland. MATE and LXQt both have some support for Wayland at this point, but haven't dropped X11 support yet. Cinnamon and XFCE has it in experimental.

We'll have to come back to this at a later point in time.