autoconf: build offline html documentation (#172103)

* autoconf: build offline html documentation

* Update pkgs/development/tools/misc/autoconf/default.nix

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

* Update pkgs/development/tools/misc/autoconf/default.nix

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

Co-authored-by: Dmitry Bogatov <git#v1@kaction.cc>
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

pkgs/development/tools/misc/autoconf/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, m4, perl }:
+{ lib, stdenv, fetchurl, m4, perl, texinfo }:
 
 # Note: this package is used for bootstrapping fetchurl, and thus
 # cannot use fetchpatch! All mutable patches (generated by GitHub or
@@ -8,6 +8,7 @@
 stdenv.mkDerivation rec {
   pname = "autoconf";
   version = "2.71";
+  outputs = [ "out" "doc" ];
 
   src = fetchurl {
     url = "mirror://gnu/autoconf/autoconf-${version}.tar.xz";
@@ -19,8 +20,15 @@ stdenv.mkDerivation rec {
     ./2.71-fix-race.patch
   ];
 
-  nativeBuildInputs = [ m4 perl ];
+  nativeBuildInputs = [ m4 perl texinfo ];
   buildInputs = [ m4 ];
+  postBuild = "
+    make html
+  ";
+
+  postInstall = "
+    make install-html
+  ";
 
   # Work around a known issue in Cygwin.  See
   # http://thread.gmane.org/gmane.comp.sysutils.autoconf.bugs/6822 for