Make mdnsd a dynamic executable.

There may have been a reason for this to be static in 2014, but those
days are long gone, and in 2021 it seems like a liability. (I came
across mdnsd after an investigation into problems people were having with
static binaries, and then trying to answer the question "how many do we
have, anyway, and do they all _need_ to be static?".)

Test: treehugger
Change-Id: Ifbb37bd4a848979cc2418681e8fea646108f743d
1 file changed