gdk: Update keyboard symbols from libxkbcommon
GTK's old key symbol list is missing a few symbols like the per mille sign (‰) that is included in some keyboard layouts. This PR updates gdkkeyuni.c to match libxkbcommon's current key symbol list.
GTK's old key symbol list is missing a few symbols like the per mille sign (‰) that is included in some keyboard layouts. This PR updates gdkkeyuni.c to match libxkbcommon's current key symbol list.