euc code in libc not aligned with localedef
The support in libc for euc encodings has special code for EUC, whereby each of the variations is handled via a "variable" which provides additional logic.
Localedef's approach is much saner, where EUC-CN, EUC-KR, EUC-JP, and EUC-TW are each treated as separate encodings.
The fact that these two are in disagreement means that none of the EUC encodings can be used.
We need to make libc's look like localedefs.
At the same time, we can remove some of the special casing checks for EUC from libc.