dev-lang/perl: Add patchlevel-gentoo to perl MANIFEST
To allow miniperl compilation, patchlevel-gentoo.h must be in the MANIFEST.
Configure uses this file to create the /host symlinks.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Comment from Gentoo perl team: Being nice here and adding this commit which
ended up without any further reasons or docs in our mailbox. I can't see how it
could hurt. I can't really see any problem that it's supposed to fix
either. Hey chromium team, more words please next time!