Replace Latin abbreviation "cf.".

People seem to be using "cf." ("confere"), which means "compare",
to mean "see" instead, for which the Latin abbreviation would be
"q.v." ("quod vide" -> "which see").

In some cases "cf." might actually be the correct term but it's
still not clear what specific aspects of a function/system call
one is supposed to be comparing.

I left one use in place in hope of obtaining clarification,
because it looks like it might be useful there, if contextualized.

Migrate these uses to English and add them to the list of
abbreviations to be avoided.

If the patch to vfork(2) is not accepted, then the cf. still needs
an \& after it because it is at the end of the line but not the
end of a sentence.

Signed-off-by: G. Branden Robinson <g.branden.robinson@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/vfork.2

@@ -297,8 +297,8 @@ system call appeared in 3.0BSD.
 .\" present, but definitely on its way out'.
 In 4.4BSD it was made synonymous to
 .BR fork (2)
-but NetBSD introduced it again,
-cf.
+but NetBSD introduced it again;
+see
 .UR http://www.netbsd.org\:/Documentation\:/kernel\:/vfork.html
 .UE .
 In Linux, it has been equivalent to

man3/clearenv.3

@@ -82,7 +82,7 @@ POSIX.1-1996 did not accept
 and
 .BR putenv (3),
 but changed its mind and scheduled these functions for some
-later issue of this standard (cf. B.4.6.1).
+later issue of this standard (see \[sc]B.4.6.1).
 However, POSIX.1-2001
 adds only
 .BR putenv (3),

man3/nl_langinfo.3

@@ -72,8 +72,8 @@ selected locale, such as "UTF-8", "ISO-8859-1", or "ANSI_X3.4-1968"
 This is the same string that you get with
 "locale charmap".
 For a list of character encoding names,
-try "locale \-m", cf.\&
-.BR locale (1).
+try "locale \-m" (see
+.BR locale (1)).
 .TP
 .BR D_T_FMT \ (LC_TIME)
 Return a string that can be used as a format string for

man3/setlocale.3

@@ -132,8 +132,8 @@ is a character set or encoding identifier like
 .B "ISO-8859-1"
 or
 .BR "UTF-8" .
-For a list of all supported locales, try "locale \-a", cf.\&
-.BR locale (1).
+For a list of all supported locales, try "locale \-a" (see
+.BR locale (1)).
 .PP
 If
 .I locale

man7/man-pages.7

@@ -799,9 +799,10 @@ when rendering a page with, say:
 .PP
      BROWSER=firefox man -H pagename
 .SS Use of e.g., i.e., etc., a.k.a., and similar
-In general, the use of abbreviations such as "e.g.", "i.e.", "etc.", "a.k.a."
-should be avoided, in favor of suitable full wordings
-("for example", "that is", "and so on", "also known as").
+In general, the use of abbreviations such as "e.g.", "i.e.", "etc.",
+"cf.", and "a.k.a." should be avoided,
+in favor of suitable full wordings
+("for example", "that is", "compare to", "and so on", "also known as").
 .PP
 The only place where such abbreviations may be acceptable is in
 .I short

man7/mq_overview.7

@@ -68,7 +68,11 @@ of the arrival of a message on a previously empty queue using
 .PP
 A message queue descriptor is a reference to an
 .I "open message queue description"
-(cf.
+.\" FIXME: "cf." means "compare".  What is we're supposed to be
+.\" comparing?  open(2) is a big page and nowhere mentions message
+.\" queues.  Aren't the relevant differences between messages queues
+.\" and files already described here, and isn't that the place for them?
+(cf.\&
 .BR open (2)).
 After a
 .BR fork (2),

man7/path_resolution.7

@@ -184,7 +184,7 @@ Linux returns
 .B ENOENT
 in this case.
 .SS Permissions
-The permission bits of a file consist of three groups of three bits, cf.\&
+The permission bits of a file consist of three groups of three bits; see
 .BR chmod (1)
 and
 .BR stat (2).