It is like test/stringcomp, only instead of using
xkb_keymap_new_from_string(), it uses xkbcomp to upload the keymap to a
dummy Xvfb X server and then xkb_x11_keymap_new_from_device().
If any of these components are not present or fails, the test is shown
as skipped.
The test is messy, fragile, limited and depends on external tools, but I
will improve on that later -- it's better to have a test.
Signed-off-by: Ran Benita <ran234@gmail.com>