bumping libpng

[wookietreiber]

hi

I recently discovered that libpng can be bumped to 1.4.8 though this requires
A LOT OF MODULES TO BE REBUILT, because of changed lib names ...

the reason I am posting this here is to ask how to bump such a module -- is
there a special way to tell users this or is checking if the build has broken
(some/many) things expected of users?

I would have used a commit message like 'run lunar fix to be sure that broken
modules will be rebuilt' though this information would reach only devs ...

best regards
wookietreiber