This update for charliecloud fixes the following issues:

Update to version 0.18

- Fixes an important symlink handling bug in ch-tug and ch-grow.
  Prior to version 0.18, if a pulled image contained a symlink in one 
  layer and then a regular file at the same path in a subsequent layer, 
  the *target* of the symlink would be overwritten even if it was 
  not within the image; i.e., unpacking inappropriately followed 
  the symlink. This allows a crafted image to overwrite any file 
  writeable by the invoking user.
  Because Charliecloud is unprivileged, other files on the system, 
  e.g. system files, are unaffected.
- ch-grow: --version and --help work w/o dependencies installed 
  new switch --list to list images
  now gives diagnostics for syntax errors and unsupported instructions
  WORKDIR now supports relative paths (#786)
  no longer crashes if input doesn’t end in newline (#474)
- miscellaneous bug fixes and improvements
- Full changelogs at https://groups.io/g/charliecloud/message/104
  and https://groups.io/g/charliecloud/message/105 

Update to version 0.16

- ch-grow and ch-tug: updates to work with external repositories
- ch-grow: COPY semantics now match Docker
- miscellaneous bug fixes and improvements
  - Full changelog at https://groups.io/g/charliecloud/message/103

This update was imported from the openSUSE:Leap:15.2:Update update project.