mgrconfig was used only by syz-manager initially,
but now it's used by a dozen of packages and it's
weird to import from under a binary dir.
pkg/ is much more reasonable dir for a widely used
helper package.
Currently kernel build failures are insanely verbose
(contain full kernel build output) and there is no
way to separate short descriptions from full output.
Make it possible.
Also try to extract failure root cause froom build log.
Use this in pkg/bisect to not pollute log on build failures.
Update #501
With 5 tries sometimes only 1 fails,
and sometimes we probably have false negatives.
Increase number of tries to 8 and compress
results if they all are the same.
Update #501
