merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/Documentation/cat-texi.perl

@@ -0,0 +1,46 @@
+#!/usr/bin/perl -w
+
+use strict;
+use warnings;
+
+my @menu = ();
+my $output = $ARGV[0];
+
+open my $tmp, '>', "$output.tmp";
+
+while (<STDIN>) {
+	next if (/^\\input texinfo/../\@node Top/);
+	next if (/^\@bye/ || /^\.ft/);
+	if (s/^\@top (.*)/\@node $1,,,Top/) {
+		push @menu, $1;
+	}
+	s/\(\@pxref\{\[(URLS|REMOTES)\]}\)//;
+	s/\@anchor\{[^{}]*\}//g;
+	print $tmp $_;
+}
+close $tmp;
+
+print '\input texinfo
+@setfilename gitman.info
+@documentencoding UTF-8
+@dircategory Development
+@direntry
+* Git Man Pages: (gitman).  Manual pages for Git revision control system
+@end direntry
+@node Top,,, (dir)
+@top Git Manual Pages
+@documentlanguage en
+@menu
+';
+
+for (@menu) {
+	print "* ${_}::\n";
+}
+print "\@end menu\n";
+open $tmp, '<', "$output.tmp";
+while (<$tmp>) {
+	print;
+}
+close $tmp;
+print "\@bye\n";
+unlink "$output.tmp";