std.posix: delete some mkdir functions

These are handled by Io.Dir now. This is part of an effort to eliminate
error.OperationCanceled from the std lib. Also an effort to delete
all std.posix functions.
0317e95aadAndrew Kelley committed on 1/4/2026, 8:27:09 AMparent2b326d2
2 files changedLine totals unavailable