Fix missing/wrong includes for BSD

Fix a few missing includes that prevented building on BSD systems.

* Client: the proper way to get MAXHOSTNAMELEN is from <sys/param.h>,
  not from <rpc/types.h>.

* Positioner/Direction: std::hash is declared in <functional>.

* Positioner/OutputNetworkSocket: get struct sockaddr from
  <sys/socket.h>, not from <netinet/in.h>.

owlps-client/owlps-client.c

@@ -33,7 +33,7 @@
 #include <signal.h>
 
 #include <net/if.h>
-#include <rpc/types.h> // for MAXHOSTNAMELEN
+#include <sys/param.h> // for MAXHOSTNAMELEN
 
 
 /* Number of packets to send */

owlps-positioner/direction.hh

@@ -15,6 +15,7 @@
 #ifndef _OWLPS_POSITIONING_DIRECTION_HH_
 #define _OWLPS_POSITIONING_DIRECTION_HH_
 
+#include <functional> // for std::hash
 #include <string>
 
 /// Represents a direction in which a mobile is when it sends a

owlps-positioner/outputnetworksocket.hh

@@ -20,7 +20,7 @@
 #include <string>
 #include <stdint.h> // <cstdint> is not C++ 98 compliant
 #include <arpa/inet.h>
-#include <netinet/in.h>
+#include <sys/socket.h> // for struct sockaddr
 
 /// Parent class for all output media that use network sockets
 class OutputNetworkSocket: public OutputMedium