Fix encoding and access of Gnus group names

* lisp/gnus/gnus-start.el (gnus-active-to-gnus-format): Encode group
  names as 'latin-1.
* lisp/gnus/nnmail.el (nnmail-parse-active): Ditto.
* lisp/gnus/nnml.el (nnml-request-group, nnml-request-create-group,
  nnml-request-expire-articles, nnml-request-delete-group,
  nnml-request-rename-group, nnml-deletable-article-p,
  nnml-active-number, nnml-open-incremental-nov): Use assoc-string
  with nnml-group-alist.
* lisp/gnus/nnrss.el (nnrss-request-delete-group,
  nnrss-retrieve-groups, nnrss-read-group-data, nnrss-check-group,
  nnrss-generate-download-script): Use assoc-string with
  nnrss-group-alist.
1 job for master in 50 minutes and 20 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1274
test-all

00:50:20

 
Name Stage Failure
failed
test-all Test
Makefile:313: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:288: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1