archivers/libarchive: Update to 3.8.7
- Drop mbedtls, depends on obsolete version that's removed in tree
- Adjust iconv dependency
- Adjust port Makefile, don't pick up libb2
Changelog: https://github.com/libarchive/libarchive/releases/tag/v3.8.7
PR: 294607
Approved by: maintainer timeout, 2+ weeks