sys-fs/lvm2: Forked to fix bug 503234

<=sys-fs/lvm2-2.02.105-r2 isn't compatible with >=sys-libs/readline-6.3.

This fork fixes the bug using a patch from upstream. For more details
see $FILESDIR/lvm2-2.02.105-readline.patch.

See also: https://bugs.gentoo.org/show_bug.cgi?id=503234