to reduce the amount of #include stuff in each single libNNN.c file.
unistd.h was added to prevent select() warnings on FreeBSD
#include <stdio.h>
#include <string.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_SYS_SELECT_H
+/* since so many tests use select(), we can just as well include it here */
+#include <sys/select.h>
+#endif
+#ifdef HAVE_UNISTD_H
+/* at least somewhat oldish FreeBSD systems need this for select() */
+#include <unistd.h>
+#endif
+
#ifndef FALSE
#define FALSE 0
#endif