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

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

third_party/git/Documentation/fix-texi.perl

@@ -0,0 +1,15 @@
+#!/usr/bin/perl -w
+
+while (<>) {
+	if (/^\@setfilename/) {
+		$_ = "\@setfilename git.info\n";
+	} elsif (/^\@direntry/) {
+		print '@dircategory Development
+@direntry
+* Git: (git).           A fast distributed revision control system
+@end direntry
+';	}
+	unless (/^\@direntry/../^\@end direntry/) {
+		print;
+	}
+}