validate: add a way to mark tests as not parallelizable
Some of my tests are using exclusive ressources (
kmssink) and so can't be run in parallel. So far my only option is to run my full tests suite with
-j 1 but some tests could still be parallelized.
It would be nice to have a setting on
GstValidateTest to mark tests which can't be run in parallel so we can serialize only those.