mountd - Add support for multiple exports files.

Taken from: FreeBSD SVN 166440
mountd - Only exit when no valid export files.

Taken from: FreeBSD SVN 168684
mountd - Add the -h <bindip> option

Taken from: FreeBSD SVN 172827
mountd - Check the correct variable after malloc()

- Also update FreeBSD Id

Taken from: FreeBSD SVN 173056
libc version maps: Update inactive symbol maps

This is a work in progress, but it is encouraging that a full buildworld
completed with a versioned libc.  This will not be activated until it is
verified with a complete bulk run of packages.