[Nice] Win32 fixes for libnice

[Tomasz Wasilczyk]

Hi,


I've been working recently on win32 build of libnice. I've made some
fixes, that I think should be pushed to upstream.

Most of these are warning fixes, some are crucial for making mingw32
build possible.

The patch:
https://dl.dropboxusercontent.com/u/5448886/contrib/mingw32-libnice.patch

The whole OBS project is accessible here:
https://build.opensuse.org/project/show?project=home%3Atomkiewicz%3Agst0

Waiting for feedback,
Tomek