Fix xkbcommon build

[joas8211]

The build for xkbcommon was failing for me without the changes in this PR.

Changes

• Remove usage of not existing xkb-base option
• Embed xkeyboard-config-2 to /usr/share/X11/xkb because there was a symlink which was not being followed

Fixed errors

1. With xkb-base option present the following error is printed:

meson.build:1:0: ERROR: Unknown option: "xkb-base".

2. Without embedding xkeyboard-config-2:

[37/37] Linking static target libxkbcommon.a
Nothing to do!
emcc: error: '/home/joas/files/projects/greenfield/libs/compositor-wasm/emsdk/upstream/emscripten/tools/file_packager ../../src/libxkbcommon.data --from-emcc --embed /home/joas/files/projects/greenfield/libs/compositor-wasm/xkbcommon/repo/share/X11@/usr/share/X11 --no-node --obj-output=/tmp/emscripten_temp_mbknamxq/embedded_files.o' failed (returned 1)

3. When embedding /usr/share/X11 with the symlink and also embedding /usr/share/xkeyboard-config-2 there was a FS error when running Compositor Shell in Firefox