We used to have issues removing tasks like do_fetch due to implications
for targets like world and universe. These have now been resolved.
Removing uneeded tasks has advantages compared to noexec since it means
that accidentally left in dependencies are no longer needed/processed
(e.g. do_patch depends on quilt-native).
This cleans up a number of cases which local analysis highlighted as
being unneeded leading to slightly cleaner task graphs.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
