[openobex] Fix null pointer ref and socket buffer size. Fixes JB#8028

- fix null pointer reference on transfer error, patch taken from
  git://gitorious.org/maemo-bluetooth/openobex-packaging.git

- ensure that send buffer for socket used in communication is
  large enough to fit any OBEX packet
Merge pull request #1 from nemomobile-packages/fix-obex-client-crash

[openobex] Fix null pointer ref and socket buffer size. Fixes JB#8028