MFH: r475268
devel/libsixel: update to 1.8.2
Fixes:
- CVE-2018-14072
- CVE-2018-14073
PR: 229975
Submitted by: sue@iwmt.org (maintainer)
Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D16421
Approved by: ports-secteam (swills)