bug#8100: Add option for dir-locals-file not to apply to subdirectories

[Glenn Morris]

Package: emacs
Severity: wishlist

Directory local variable files are really "project" local variable
files, in that they apply to all subdirectories below a given directory.
There ought to be a way to mark a directory locals file such that it
only applies to the directory it is in, not to any subdirectories.

Strictly speaking, the addition of this feature is necessary for
dir-locals-file to be a complete replacement for Dired-X's
dired-local-variables-file feature.