Add #define XK_SINHALA so that the Sinhala keysyms can be used by
the lk xkb keymap.
Signed-off-by: Harshula Jayasuriya <harshula@gmail.com>
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
Backported-to-NX-by: Ulrich Sibiller <uli42@gmx.de>