Add <sys/types.h> for off_t.

This shouldn't be necessary, but apparently on OS X 10.4 fseeko()
 takes fpos_t instead of off_t, and thus doesn't guarantee that
 off_t is defined.

src/stream.c

@@ -15,6 +15,7 @@
 
  ********************************************************************/
 #include "internal.h"
+#include <sys/types.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>