textproc/iksemel: fix build when openssl is installed.

This port does not build when openssl is installed. Disable it explicitely in
the configure.

PR: 254296
Reported by: dym@afalina.od.ua
Tested by: felix@palmen-it.de newton.ja.terry@gmail.com
MFH: 2021Q2 build fix

(cherry picked from commit 0a4dd56b6717f75db19a03d8a7920783e256cd0a)