Resolution of bug #997368, "strftime() backward compatibility".

Specifically, time.strftime() no longer accepts a 0 in the yday position of a
time tuple, since that can crash some platform strftime() implementations.

parsedate_tz(): Change the return value to return 1 in the yday position.

Update tests in test_rfc822.py and test_email.py
diff --git a/Lib/rfc822.py b/Lib/rfc822.py
index 3811a59..3b4246d 100644
--- a/Lib/rfc822.py
+++ b/Lib/rfc822.py
@@ -927,7 +927,7 @@
         else:
             tzsign = 1
         tzoffset = tzsign * ( (tzoffset//100)*3600 + (tzoffset % 100)*60)
-    tuple = (yy, mm, dd, thh, tmm, tss, 0, 0, 0, tzoffset)
+    tuple = (yy, mm, dd, thh, tmm, tss, 0, 1, 0, tzoffset)
     return tuple