bug: `glfw-sys` enables all features by default (making ``wayland`` a requirement)

[davidhozic]

glfw-rs lists glfw-sys as a dependency, however it doesn't disable any of it's features.
Thus all of its default features are enabled:

["x11", "wayland", "native-handles", "native-gl", "native-egl", "vulkan"]

This leads to problems where wayland isn't installed, as it tries to use its libraries:

thread 'main' panicked at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/glfw-sys-6.0.0/build.rs:114:26:
pkg-config failed to find wayland-client: 
pkg-config exited with status code 1
> PKG_CONFIG_ALLOW_SYSTEM_LIBS=1 PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1 pkg-config --libs --cflags wayland-client

The system library `wayland-client` required by crate `glfw-sys` was not found.
The file `wayland-client.pc` needs to be installed and the PKG_CONFIG_PATH environment variable must contain its parent directory.
The PKG_CONFIG_PATH environment variable is not set.