update-directory-autoloads ends up thinking it is a "secondary" autoload
file, so it puts MD5 checksums instead of timestamps.
* el-get-autoloading.el (el-get-update-autoloads): use
find-buffer-visiting instead of get-file-buffer to detect buffers
visiting .loaddefs via non-standard path, and call kill-buffer if we
find such buffers.
package.el uses <pkg-name>-autoloads.el as the destination for autoloads
generated from cookies. Meaning that during a MELPA bootstrap install
these get appended to el-get-autoloads.el. Although it's currently
harmless during bootstrap, better to avoid any possible future problems.