patman: separate emails in CC list with NULs

There is a contributor in Linux kernel with a comma in their name, which
confuses patman and results in invalid to- or cc- addresses on some
patches. To avoid this, let's use \0 as a separator when generating cc
file.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/series.py b/tools/patman/series.py
index 67103f0..d667d9b 100644
--- a/tools/patman/series.py
+++ b/tools/patman/series.py
@@ -243,13 +243,13 @@
             if limit is not None:
                 cc = cc[:limit]
             all_ccs += cc
-            print(commit.patch, ', '.join(sorted(set(cc))), file=fd)
+            print(commit.patch, '\0'.join(sorted(set(cc))), file=fd)
             self._generated_cc[commit.patch] = cc
 
         if cover_fname:
             cover_cc = gitutil.BuildEmailList(self.get('cover_cc', ''))
             cover_cc = [tools.FromUnicode(m) for m in cover_cc]
-            cc_list = ', '.join([tools.ToUnicode(x)
+            cc_list = '\0'.join([tools.ToUnicode(x)
                                  for x in sorted(set(cover_cc + all_ccs))])
             print(cover_fname, cc_list.encode('utf-8'), file=fd)