emacs hangs in idna-to-ascii

[Hugh Daschbach]

With libidn 1.28 installed, starting "gnus" in emacs 24.3.1, causes
emacs to hang until keyboard-quit.  It seems idna-to-ascii is waiting
for output from the idn process.

Looks like output to stdout (a pipe provided by emacs) is buffered.
An fflush(stdout) at the bottom of the read/eval/print loop seems to
fix this:

--- a/src/idn.c 2013-10-04 13:55:55.918357293 -0700
+++ b/idn.c     2013-10-04 13:55:50.618386005 -0700
@@ -568,6 +568,7 @@
 
          free (p);
        }
+      fflush(stdout);
     }
   while (!feof (stdin) && !ferror (stdin) && (args_info.inputs_num == 0 ||
                                              cmdn < args_info.inputs_num));