Make it possible to build on Octave (Windows).
Make it possible to build on Octave (Windows).

Tested on Octave 4.0.0 32-bit (official build) and 64-bit (custom build, using --enable-windows-64) and OpenCV 3.0.0 (final), which was built using MinGW (there were some errors when building, mostly due new calling conventions on this version)
nanit/mexopencv,nanit/mexopencv,fengzhyuan/mexopencv,CVML/mexopencv,CVML/mexopencv,bearpaw/mexopencv,bearpaw/mexopencv,fengzhyuan/mexopencv