bug#18475: 24.4.50; Wdired: cannot use C-k to delete a dir name if -F switch used

[Drew Adams <drew.adams@oracle.com>]

The `wdired-mode' doc string says: "If you delete the filename of a
file, it is flagged for deletion in the Dired buffer."  And (emacs)
`Wdired' says: "To mark a file for deletion, delete the entire file
name."

And this applies to directory names also.

No problem, except if you use `ls' switch `-F', which appends `/' to
directory names.  In that case, if you try to use `C-k' anywhere on the
dir name text, you get the error "Text is read only".

(Yes, you can use other deletion keys besides `C-k' to delete the dir
name but not delete the `/'.  That looks weird and is not easily
guessable by users, but it works.  `C-k' should work also, as one would
expect.)

In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-08-15 on LEG570
Bzr revision: 117706 rgm@gnu.org-20140815043406-p5hbu97cbm7pulcn
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking 'CFLAGS=-O0 -g3' CPPFLAGS=-DGLYPH_DEBUG=1'