Unit test fixes for MSVC, glib_checks=disabled and glib from git master
My hackathon project this year was to make sure all the core-tests were running on MSVC.
However, we compile core with glib_checks=disabled, and then a lot of the tests were not running on Linux either.
Now, if GStreamer binaries are released with glib_checks=disabled, it feels wrong to not run any tests against them, even though some tests will not apply in the same way, since you won't get a "critical".
With these commits the tests run on MSVC and Linux with glib_checks both enabled and disabled.