Look in libsocket for socket functions on Solaris

CMakeLists.txt

@@ -258,6 +258,9 @@ if(WIN32)
   set(HAVE_INET_ATON 1)
   set(HAVE_GETADDRINFO 1)
 else()
+  if(${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
+    set(CMAKE_REQUIRED_LIBRARIES socket)
+  endif()
   check_function_exists(inet_aton HAVE_INET_ATON)
   check_function_exists(getaddrinfo HAVE_GETADDRINFO)
   set(CMAKE_REQUIRED_LIBRARIES)