Get rid of the time during the while loop and just let this run forever
in case of a failure and also bump the timeout in meson to 60 seconds
since we know it is possible for msys to take a very long time on
occasion. That should be plenty of time for it to finish.
We already have a libmpv test, but it's really basic and barely does
anything. In an effort to hopefully prevent future breakage, lets expand
this to do more stuff. First of all, it simply tests setting a bunch of
properties/options. Secondly, it tries to load a file (the mpv icon that
we already have in the source tree). And then finally it tries the
lavfi-complex filter since this is a known special case where weird
things can happen.
This reworks all of mpv's unit tests so they are compiled as separate
executables (optional) and run via meson test. Because most of the tests
are dependant on mpv's internals, existing compiled objects are
leveraged to create static libs and used when necessary. As an aside, a
function was moved into video/out/gpu/utils for sanity's sake (otherwise
most of vo would have been needed). As a plus, meson multithreads
running tests automatically and also the output no longer pollutes the
source directory. There are tests that can break due to ffmpeg changes,
so they require a specific minimum libavutil version to be built.