Ǫ (U+01EA, O with ogonek),
Ȩ (U+0228, E with cedilla),
Ȯ (U+022E, O with dot above),
Ạ (U+1EA0, A with dot below), and
their lowercase forms do not occur in any layout of xkeyboard-config,
meaning that the compose sequences that contained these letters could
not be typed. Delete their dead weight.
Signed-off-by: Benno Schulenberg email@example.com