Split inet_pton internals such as __inet_pton_length from the
inet_pton entry point.
This allows the internals to be built with fortification while
leaving the inet_pton entry point unchanged.
Co-authored-by: Frédéric Bérat <fberat@redhat.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Aaron Merey