t/103-unicode: workaround unicode normalization on newer macOS.

As named, the file would be extracted by git on macOS, then
(un)helpfully normalized by the macOS filesystem. After that,
"git clean -fdx" would delete the file, since it no longer
had the expected name, so git thought it wasn't part of its repo.

I considered pre-normalizing the filename, but a) that would break
on any future OS that normalizes differently; and b) that means we
won't test denormalized filenames. Instead, we'll remove the directory
from git, and create it from sh instead, then figure out what name
it got really created as, and then pass the "real" name to redo.

t/103-unicode/clean.do

@@ -0,0 +1 @@
+rm -rf *.tmp