Fix compression of directories in Dired

Fix compression of directories in Dired

This fixes comporession and uncompression of directories on
MS-Windows, but also on other systems.  The original code used
":" as the REGEXP of the directory entry in
dired-compress-file-suffixes, which on Windows always matched any
absolute file name, and can also match unusual file names on Posix
hosts.  This false match would cause dired-compress-file to act as
if we are decompressing a directory, but use a command suitable
for compression, which would fail in interesting ways.
We now use a REGEXP that can never match any valid file name.

* lisp/dired-aux.el (dired-compress-file-suffixes): Make the
"compress directory" entry's REGEXP really fail to match any valid
file name.
(dired-compress-file): Adapt to the change in
dired-compress-file-suffixes.  (Bug#39024)
(dired-compress): If the current file is a directory, or if the
uncompressed file is a directory, don't remove the original from
the listing, since it is left in the filesystem.