git/gitignore: Only ignore `build' etc. if they're toplevel directories.
[profile] / el /
drwxr-xr-x   ..
-rw-r--r-- 141753 dot-emacs.el
-rw-r--r-- 6065 mdw-gnus-patch.el
-rw-r--r-- 6026 mdw-multiple-cursors.el