Update libvterm.so

libvterm tip:

    ------------------------------------------------------------
    revno: 624
    revision-id: leonerd@leonerd.org.uk-20141228225257-zvih256n2m86ogdy
    parent: leonerd@leonerd.org.uk-20141228151101-nkpzlusjbyc6bpl4
    committer: Paul "LeoNerd" Evans <leonerd@leonerd.org.uk>
    branch nick: libvterm
    timestamp: Sun 2014-12-28 22:52:57 +0000
    message:
      Rename vterm_push_bytes() to vterm_input_write(); return written size
Merge branch 'travis-49.8' into master