check: Avoid forking for good
As part of investigating a deadlock with glib 2.64 and running tests : gst-plugins-good#626 (comment 488073)
We really need to stop screwing around with forking and multi-threading:
- We will hit issues like the one explained in that link
- We have sync issues between runner and child if test finishes too quickly
The advantage of forking for each test though is that it ensures a "clean" environment for each "unit" test.
I propose we figure out a way to avoid forking, and instead switch to "spawning" a clone. The "master" process would then instruct the "child" process what to do, and control timeouts. But no more forking.