Description
GL backend does not work on Wayland.

Repro steps
0. wgpu repository

1. WGPU_BACKEND=gl cargo run --example cube panics
2. WAYLAND_DISPLAY= WGPU_BACKEND=gl cargo run --example cube works

Expected vs observed behavior
Expected: Both Wayland and X11 (Xwayland) work with both Vulkan and GLES
Got: Wayland only works with Vulkan, X11 is fine with both

Error: [2021-12-30T12:23:13Z ERROR wgpu_core::device] surface configuration failed: incompatible window kind

Extra materials
I'm going to investigate the issue on my own currently and submit a PR in case of successful fix.

Platform
GNOME Shell/Mutter 41.2 on Fedora 35
AMDGPU (Ryzen 4500U)
wgpu from master branch