Revert "m4: build offline documentation"

This reverts commit bde8c13bb2.

pkgs/development/tools/misc/gnum4/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, texinfo4 }:
+{ lib, stdenv, fetchurl }:
 
 # Note: this package is used for bootstrapping fetchurl, and thus
 # cannot use fetchpatch! All mutable patches (generated by GitHub or
@@ -8,9 +8,6 @@
 stdenv.mkDerivation rec {
   pname = "gnum4";
   version = "1.4.19";
-  outputs = [ "out" "doc" ];
-
-  nativeBuildInputs = [ texinfo4 ];
 
   src = fetchurl {
     url = "mirror://gnu/m4/m4-${version}.tar.bz2";
@@ -25,15 +22,6 @@ stdenv.mkDerivation rec {
   configureFlags = [ "--with-syscmd-shell=${stdenv.shell}" ]
     ++ lib.optional stdenv.hostPlatform.isMinGW "CFLAGS=-fno-stack-protector";
 
-  postBuild = ''
-    makeinfo --html --no-split doc/m4.texi
-  '';
-
-  postInstall = ''
-    mkdir -p $doc/share/doc/m4
-    cp ./m4.html $doc/share/doc/m4
-  '';
-
   meta = {
     description = "GNU M4, a macro processor";
     longDescription = ''