Particular DIR commands like: "DIR .", "DIR .." now work as expected,
and we also correctly fix the behavior for files without extension,
that r38746 (2b06cfc0) originally tried to fix but broke the previous
examples.
Therefore "DIR *." and "DIR noextfile." work too.
Pathological cases like "DIR \...", "DIR \...\.", "DIR ..\...\.." and
the like (and with more than 3 dots) now work as expected.
Adapted from PR #592 by Katayama Hirofumi MZ, but with extended bugfixing.
CORE-13961