(trunk libT) copyediting: remove a bunch of seemingly-unneeded network headers in net.[ch].

I'm less certain that these are unneeded because networking APIs seem to have more variation between platforms, but it's better to remove the cruft and then add back whatever headers $PLATFORM users complain about, than to not remove the cruft at all...

utils/show.c

@@ -10,7 +10,7 @@
  * $Id$
  */
 
-#include <stdio.h>
+#include <stdio.h> /* fprintf() */
 #include <string.h> /* strcmp(), strchr(), memcmp() */
 #include <stdlib.h> /* getenv(), qsort() */
 #include <time.h>