[RFC] contrib: split some makefile to have one file with source unpacking rules

This way if the rules change, it's considered the source package must be updated and rebuild.

The package will be unpacked (+ patched) in those cases:

• it was never unpacked
• the version changed
• the patching rules changed (including adding/removing sed patching)
• patches have been modified, provided they include the proper dependency

This MR (currently) doesn't modify all the contribs, but it can be done gradually