Remove useless use of <assert.h>.

These files #included <assert.h> but didn't ever use assert.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>

lib/stream-unix.c

@@ -16,7 +16,6 @@
 
 #include <config.h>
 #include "stream.h"
-#include <assert.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <netdb.h>