dns/ldns: Fix SSL library support, tidy options

The makefile for the ldns was very hard to follow due to preprocessor-
like hunks changing the logic flow even across targets. As part of the
SSL fix, I felt compelled to convert much of the options logic to the
modern options framework to make it simpler to follow the makefile
logic (as a side benefit the port is a bit more tidy).

I also reworked the FreeBSD 9 + GOST option logic to set the new
IGNORE_FreeBSD_9 variable if GOST was requested on FreeBSD 9 with the
base SSL library. I believe the previous logic using the WITH_OPENSSL_PORT
knob and CONFLICTS setting was incorrect.

Approvd by: SSL blanket