sysutils/getssl: add missing RUN_DEPENDS

ftp/curl and dns/bind-tools are required. Also while here, pet some portlint
warnings.

PR: 232918 235351
Submitted by: Rainbow <rainbow@sanitylinux.org> (maintainer)
Reported by: Andrew <pez_098@yahoo.com>, oz42@oz42.eu
MFH: 2019Q1
Differential Revision: https://reviews.freebsd.org/D17954