[meld] Fix using multiprocessing while freezed (for windows installer).

[Kai Willadsen <kaiw src gnome org>]

commit f840d342b55bd690f7191ec584edd8c057f95d31
Author: galkinvv <galkin-vv ya ru>
Date:   Tue Oct 10 04:26:25 2017 +0300

    Fix using multiprocessing while freezed (for windows installer).

 bin/meld |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/bin/meld b/bin/meld
index bb88aa6..307766c 100755
--- a/bin/meld
+++ b/bin/meld
@@ -22,6 +22,11 @@ import os
 import signal
 import subprocess
 import sys
+from multiprocessing import freeze_support
+
+# Main module hasn't multiprocessing workers, so not imported in subprocesses.
+# This allows skipping '__name__ == "main"' guard, but freezed case is special.
+freeze_support()
 
 # On Windows, pythonw.exe (which doesn't display a console window) supplies
 # dummy stdout and stderr streams that silently throw away any output. However,