Bug 1065252 - Ignore Emacs .dir-locals.el. r=ted

Ignore Emacs's directory variable files .dir-locals.el in all directory.
It allows me to write ((c-mode . ((mode . c++)))) to view all .h files
in C++ mode especially for those .h files generated by IDL without
proper Emacs modeline.

DONTBUILD because NPOTB

.gitignore

@@ -12,6 +12,9 @@ ID
 # Vim swap files.
 .*.sw[a-z]
 
+# Emacs directory variable files.
+**/.dir-locals.el
+
 # User files that may appear at the root
 /.mozconfig*
 /mozconfig

.hgignore

@@ -11,6 +11,9 @@
 ^\.sw.$
 .[^/]*\.sw.$
 
+# Emacs directory variable files.
+\.dir-locals\.el
+
 # User files that may appear at the root
 ^\.mozconfig
 ^mozconfig*