Problem: test_stream_exceeds_buffer has redundant includes

Solution: remove them as they are already in testutil.hpp

tests/test_stream_exceeds_buffer.cpp

@@ -34,15 +34,8 @@
 #   include <ws2tcpip.h>
 #   include <stdexcept>
 #   define close closesocket
-#else
-#   include <sys/socket.h>
-#   include <netinet/in.h>
-#   include <arpa/inet.h>
-#   include <unistd.h>
 #endif
 
-#include <zmq.h>
-
 int main()
 {
     const int msgsize = 8193;