Windows: Remove -g debug flag for building all mex files on Windows to fix various problems.

Matlab documentation about debugging mex files states that "mex files
built with the -g option will not work on other computers". This is not
really true, but it it true that such files can apparently cause a lot
of trouble.

After removing the -g flag from our build scripts for Windows and
rebuilding Screen, suddenly all remaining GStreamer related problems,
hangs and crashes are resolved! Even writing of movie files in
ImagingStereoDemo with/without sound track now creates valid files and
no longer hangs/deadlocks or crashes Matlab. Looped movieplayback of
all files, including DualdDiscs.mov, and manual texture fetching via
LoadMovieIntoTexturesDemo works with all files. The only untested thing
is video capture and recording, as i can't get any usb webcam to work
within the VirtualBox Windows VM, but this seems to be a Windows+VM
problem, not a GStreamer problem, as the bundled standalone test app of
the Webcam doesn't work properly either.

As a cautionary measure, all mex files for 32/64-Bit Matlab for Windows
have been rebuilt, so we don't ship any mex files for Windows with
debug build anymore.