vendor/libarchive: upgrade from 3.4.3 to 3.6.1

vendor/libarchive: upgrade from 3.4.3 to 3.6.1

Notable changes:

 - 7zip reader: fix PPMD read beyond boundary (#1671)
 - ZIP reader: fix possible out of bounds read (OSS-Fuzz 38766 #1672)
 - ISO reader: fix possible heap buffer overflow in read_children()
 - tar: new option "--no-read-sparse" (#1614)
 - ZIP reader: zstd decompression support (#1518)
 - extended fix for following symlinks when processing the fixup
   list (#1566, #1617, CVE-2021-31566)
 - fix invalid memory access and out of bounds read in RAR5 reader
   (#1491, #1492, #1493, CVE-2021-36976)
 - ZIP reader: Support of deflate algorithm in symbolic link
   decompression (#1509)
 - do not follow symlinks when processing the fixup list (#1566)
 - fixed extraction of archives with hard links pointing to itself (#1381)
 - fixed memory leaks in error case of archive_write_open() functions (#1456)

For details, see release notes or commit history on github:
 https://github.com/libarchive/libarchive/releases/tag/v3.6.1