[Libreoffice] New tinderbox: MinGW cross-compilation

Hi all,

Thanks to Tor's cross-compilation work [1], and Fridrich's MinGW Open
Build Service packages [2], I was able to get the compilation of Windows
MinGW packages on Linux to a state that it builds all the way up to
instsetoo_native quite reliably.  So I've setup a tinderbox that ensures
that this is not going to bitrot ;-) - see "MinGW cross-compilation" at

http://tinderbox.libreoffice.org/MASTER/status.html

Updated build instructions are here:

http://cgit.freedesktop.org/libreoffice/core/tree/README.cross

If you are interested in hacking on this, this is a copy of the TODO
part:

- installation
  - so far the make_installer.pl calls makecab.exe, uuidgen.exe, and
    others; would be best to avoid that if at all possible (using a free
    cab implementation, part of Wine or something)
  - MSI generation
  - if at all possible, the make dev-install installation (with links
    back to the build) should be done so that it would be directly
    executable via wine after doing make dev-install :-)

- runtime
  - no idea if the entire thing works after the installation at all; I
    suppose there will be runtime problems to look at too

- cleanup
  - enable & fix pieces that are currently disabled
    - --without-myspell-dicts
    - --disable-directx
    - --disable-activex 
    - --disable-mozilla
  - much of the stuff currently relies on --with-system-*, and
    consequently on the mingw32-* openSUSE packages; might be good to be
    able to build with as few dependencies as possible - but that is low
    prio I think

- profiling
  - when all the above is sorted out, we should look at the speed of
    this vs. the speed of the MSVC version

Patches most welcome! :-)

[1] http://tml-blog.blogspot.com/2011/06/cross-compiling-libreoffice-to-ios.html
[2] http://download.opensuse.org/repositories/windows:/mingw:/win32/

Regards,
Kendy