Compile DIAL client and server for macOS.

Changes:
* Added method to get mac and ip address for OSX. Current Linux method
of query via SIOCGIFCONF doesn't work. Added code to read via getifaddrs() API.
* Put non OSX specific code under #ifdef flags.
* Removed few linker libraries which are not required (lcares and lrt).
* Fixed many warnings.

Tested on: OSX 10.12

client/DialDiscovery.h

@@ -28,6 +28,7 @@
 
 #include "DialServer.h"
 #include <map>
+#include <pthread.h>
 
 using namespace std;
 
@@ -82,9 +83,6 @@ private:
     void cleanServerList();
     void resetDiscovery();
 
-    pthread_t _mcastThread;
-    pthread_t _responseThread;
-
     typedef map<string, DialServer*> ServerMap;
     ServerMap mServerMap;