lisp/gnus/.dir-locals.el

[Eli Zaretskii]

Addition of this file triggers the following warning message when
compiling in the lisp subdirectory:

  In toplevel form:
  gnus/.dir-locals.el:1:1:Warning: `(emacs-lisp-mode (show-trailing-whitespace
      . t))' is a malformed function

FWIW, I don't understand why this file was added in the first place.
The commit message gives a reason, but I don't see how it justifies
this file in this single directory; it sounds more like personal
preferences, which should not be in the repository.

In addition, the change is not mentioned in the ChangeLog.

At the very least, the file should be marked as "no-byte-compile", or
something else should be done to avoid this warning.