#11554: reactivate test_email_codecs, and make it pass.

The fix is to charset.py, which was not doing the encoding to the
correct output character set when doing a body_encode for either
the shift-jis or euc-jp charsets.  There's also a fix for handling
a bytes input in encoders.py.

Patch by Michael Henry, comment changes by me.
diff --git a/Lib/test/test_email.py b/Lib/test/test_email.py
index f0a18e7..5eebba5 100644
--- a/Lib/test/test_email.py
+++ b/Lib/test/test_email.py
@@ -3,10 +3,12 @@
 
 # The specific tests now live in Lib/email/test
 from email.test.test_email import suite
+from email.test.test_email_codecs import suite as codecs_suite
 from test import support
 
 def test_main():
     support.run_unittest(suite())
+    support.run_unittest(codecs_suite())
 
 if __name__ == '__main__':
     test_main()