In some cases (Travis), sources and build caches may be moved around in-between
builds, and we can't necessarily trust that everything is still intact.
This introduces pre-build checks that verify against stashed checksums.
Note that this will cause all sources to be re-downloaded, since cached sources
weren't trustworthy before this.
Broken hash logic caused all depends on some platforms (osx at least) to end up
with the same build-id. Without this fix, nothing will be rebuilt when recipes
or dependencies change.
Since the last commit will force rebuilds of all depends, take the opportunity
to clean up a few other things that would trigger rebuilds as well.
- Move source stamps to the sources dir so that SOURCES_PATH is respected for
"make download".
- Only print "fetching..." when actually downloading a file.
- Avoid using non-deterministic paths for the recipe hash (patch location).
This should ensure that all builders get the same resulting build-ids.
- Use a per-package source paths. This will allow for removing old source files
in the future.
- Use a host-agnostic path for downloads which gets cleaned up properly.
Some sources are renamed after download, since the filenames don't play nice
with (for example) gitian. This fixes the rename.
Needed for OSX build as it renames a file.
