[REVIEW 3-6-1] fdo#52078 Explorer crashes on Flat ODF files

Hi,

Windows Explorer shell extension of LibreOffice, which displays
document metadata and thumbnail image of ODF files in Windows
Explorer, crashed when the view contained Flat ODF files.

As a quick fix, I disabled registration of shell extension for Flat ODF files.
http://cgit.freedesktop.org/libreoffice/core/commit/?id=68909d3d25da0fe350319dfc82ca5b8fe9f38dc8

Fridrich rewrote zip file handling in shell extension in order to
avoid the need of minizip. I did not check how it worked in 3.5, but
now shell extension tries to find a zip structure even in Flat ODF
files, and fails miserably. 3.5 does not crash, but it does not show
Flat ODF properties either. So the patch above is safe to apply.
However, crash can be triggered any time, when an ODF file is
corrupted, e.g. rename any random file to .odt extension and watch the
crash. So shell/source/win32/zipfile/zipfile.cxx needs to be patched,
too. I leave that to Fridrich. :)

Best regards,
Andras