Don't build mdnsd for Windows.

We don't have an LLVM replacement for windmc (though there is an
llvm-windres), but it seems like the only "user" is itself unused, so
the easy option is to just stop building that...

Bug: http://b/203794880
Test: treehugger
Change-Id: I4a933be8bf3471f6866aecb33616ad126f9d54d8
1 file changed