Ignore all dot-files in .gitignore

* .gitignore: Ignore all dot-files except for those checked into Git.
This makes us less opinionated about using tools in the Emacs tree.

.gitignore

@@ -18,9 +18,15 @@
 # along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 
 
-# Personal customization.
-.dir-locals-2.el
-.no-advice-on-failure
+# Ignore all dot-files except for those under version control.
+.*
+!.clang-format
+!.clangd
+!.dir-locals.el
+!.gitattributes
+!.gitignore
+!.gitlab-ci.yml
+!.mailmap
 
 # Built by 'autogen.sh'.
 /aclocal.m4
@@ -314,7 +320,6 @@ gnustmp*
 *.orig
 *.swp
 *~
-.#*
 \#*\#
 ChangeLog
 [0-9]*.patch
@@ -363,17 +368,8 @@ lib-src/seccomp-filter-exec.pfc
 # Ignore directory made by admin/make-manuals.
 /manual/
 
-# Ignore Finder files on MacOS.
-.DS_Store
-
-# Ignore a directory used by dap-mode.
-.vscode
 /test/gmp.h
 
-# GDB history
-.gdb_history
-_gdb_history
-
 # Files ignored in exec/.
 exec/aclocal.m4
 exec/config.guess