Log Message:
pkgin: Update to 0.16.1.

The "jperkin should have run the test suite before releasing 0.16.0" \ 
release.

## Version 0.16.1 (2020-04-29)

 * Don't attempt to update the keep list if we're only downloading packages.
 * Avoid C99isms for now, fixes CentOS 6 build.
 * Ignore "pkg_admin rebuild-tree" output, removes spurious \ 
"Done." messages
   from output.
 * Some minor internal refactoring.