archivers/libarchive: Update to 3.6.2

• Backport upstream commit 1f35c466aaa9444335a1b854b0b7223b0d2346c2 to fix iconv issue with .pc file
• Patch .pc file when compiled on versions of FreeBSD where we don't provide a .pc file for OpenSSL

Changelog: https://github.com/libarchive/libarchive/releases/tag/v3.6.2

PR: 268693
Reviewed by: glewis (maintainer)