Update to 0.58

Upstream changes:
0.58: Nov 25, 2018

  - on inflate error, first return any remaining bytes before returning the error.

  - remove leading "./" even if ac->currentDir[] is not set; change mirrors a
    change in rsync-bpc and has no effect here since BackupPC::XS doesn't set
    ac->currentDir[].

  - bpc_attrib_dirWrite() updates dir->digest with new digest.

  - updated configure.sh with package name and current version

(wen)