Fix distutils’ check and register Unicode handling (#13114).

The check command was fixed by Kirill Kuzminykh.

The register command was using StringIO.getvalue, which uses “''.join”
and thus coerces to str using the default encoding (ASCII), so I changed
the code to use one extra intermediary list and correctly encode to
UTF-8.
diff --git a/Misc/ACKS b/Misc/ACKS
index b7e34de..856afaa 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -469,6 +469,7 @@
 Andrew Kuchling
 Ralf W. Grosse-Kunstleve
 Vladimir Kushnir
+Kirill Kuzminykh (Кирилл Кузьминых)
 Ross Lagerwall
 Cameron Laird
 Łukasz Langa