extract-utils: Add pinning support

 * In many cases, we would like to keep certain files which do not
   exactly match what might be extracted from a factory ROM. This
   becomes extremely annoying over time to manually reconstruct,
   and it's easy to miss these special cases when updating to a
   new vendor release. It's also useful to flag additions which
   aren't found in the upstream release at all.
 * To solve this, we can now "pin" files to a specific sha1 hash.
   Simply append the sha1sum of the file to the appropriate line
   in your bloblist, prepended by a | delimiter.
 * This works by backing up the current files first, running the
   extraction, then checking if any pinned files need to be
   restored.
 * Also add an exit trap to clean up all of our tempfiles

Change-Id: I2010b5175b5701e19a3efb112e8907062ca37d66

0 files changed, 0 insertions, 0 deletions