Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Pull up vendor changes. The following local changes made obsolete:

- Addition of several FreeBSD versions.
- r192561 that attempted to fix UTF-8 issues.

When man pages are formatted in UTF-8, .Fl is encoded as U+2212 "MINUS
SIGN" instead of U+002D "HYPHEN-MINUS". This is unfortunate for two
reasons: 1) this is not the character which is actually used on the
command line, and 2) it makes it impossible to search a man page for a
specific command-line option.

This patch fixes this, but there are other unresolved issues, such as
confusion between -, \- and hy: while the latter is always (and only)
used for hyphenation, both - and \- are used for negation and
subtraction, and \- is used for command-line options and sometimes
also for parenthesis. IMHO, the correct Unicode characters are:

- hyphenation: either U+2010 or U+00AD, most likely the former (the
latter is the so-called soft hyphen, used to indicate a point at
which a text processor is allowed to hyphenate a word)

- negation and subtraction: U+2212

- parenthesis: in English, U+2214, with spaces suppressed before and
after; in some others (such as Norwegian), U+2213 with spaces
retained.

- command-line options: U+002D, because that is what is actually used
on the command line.

However, fixing this would require extensive modifications to (at least)
the doc and man macro sets...

MFC after: 1 week

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