We have a single character-encoding test that is cloned 3x so we can
exercise the different values for the project's default character
set. It was a 65816 test because it tested 16-bit immediate char
operands, but that's a very small part of it.
The 65816-specific portion is now 20122-char-encoding. The rest is
now 201{2,3,4}0-char-encoding-X.