Fixes:
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* Fix "man -X75-12" and "man -X100-12" to set the document font size
(using "-rS12") as well as the device (using "-TX75-12" or
"-TX100-12").
* Fix incompatibility of "man -X" and friends with the seccomp
sandbox.
Improvements:
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* Add a bug tracker link to man-db's own manual pages.
* Add support for zstd-compressed manual pages, thanks to Bernhard
Rosenkränzer.