Merge upstream 5.23.

Merge upstream 5.23.
(cperl-where-am-i): Remove function.
(cperl-backward-to-noncomment): Don't go too far when skipping POD/HEREs
(cperl-sniff-for-indent): De-invert [string] and [comment].
When looking for label, skip s:m:y:tr.
(cperl-indent-line): Likewise.
(cperl-mode): Don't assume `font-lock-multiline' is auto-local.
(cperl-windowed-init): Wrong `ps-print' handling.
Both thanks to Chong Yidong.
(cperl-look-at-leading-count): Could fail with unfinished RExen.
(cperl-find-pods-heres): If the second part of s()[] is missing,
don't try to highlight delimiters...