* nnheader.el (nnheader-find-file-noselect): Call

* nnheader.el (nnheader-find-file-noselect): Call
`find-file-noselect-as-coding-system' with CODING-SYSTEM as the 1st arg.

* nnmail.el (nnmail-find-file): Call `insert-file-contents-as-coding-system'
with CODING-SYSTEM as the 1st arg.
* nnheader.el (nnheader-insert-file-contents): Likewise.

* gnus-start.el (gnus-save-newsrc-file): Call `write-region-as-coding-system'
with CODING-SYSTEM as the 1st arg.
(gnus-read-newsrc-el-file): Call `insert-file-contents-as-coding-system' with
CODING-SYSTEM as the 1st arg.

* gnus-cache.el (gnus-cache-save-buffers): Call
`gnus-write-buffer-as-coding-system' with CODING-SYSTEM as the 1st arg.

* gnus-util.el (gnus-write-buffer-as-coding-system): Be CODING-SYSTEM the 1st
arg.

* nnmail.el (nnmail-write-region): Call `write-region-as-coding-system' with
CODING-SYSTEM as the 1st arg.
* gnus-start.el (gnus-save-newsrc-file): Likewise.
* gnus-agent.el (gnus-agent-expire): Likewise.
(gnus-agent-fetch-headers): Likewise.
(gnus-agent-flush-cache): Likewise.
(gnus-agent-fetch-articles): Likewise.
(gnus-agent-save-history): Likewise.
(gnus-agent-save-groups): Likewise.
(gnus-agent-save-active): Likewise.