Add header-present guards to include of sys/time.h.

I'm not sure why this hasn't been hit before - it breaks the build on
Windows. I guess that another change has started dragging in this file
where it wasn't used before.

Author: Jim Hague

src/gldns/wire2str.c

@@ -26,7 +26,9 @@
 #ifdef HAVE_TIME_H
 #include <time.h>
 #endif
+#ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
+#endif
 #include <stdarg.h>
 #include <ctype.h>
 #ifdef HAVE_NETDB_H