package/libarchive: security bump to version 3.4.2

package/libarchive: security bump to version 3.4.2

- Fix CVE-2020-9308: archive_read_support_format_rar5.c in libarchive
  before 3.4.2 attempts to unpack a RAR5 file with an invalid or
  corrupted header (such as a header size of zero), leading to a SIGSEGV
  or possibly unspecified other impact.
- use --with-nettle to enable nettle support, see
  https://github.com/libarchive/libarchive/commit/f96a71144b7725ca4a94d84bd27d7dca8c2f58d2

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr:
  - drop new optional dependency to mbedtsl, forced off for now
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>