binutils: avoid texinfo dependency during bootstrap

Normally binutils provides pregenerated manuals along with release
tarball. Manuals regeneration is needed every time we change
`configure.ac`. But usually there are no material changes in it.

This change instead inhibits manuals regeenration by keeping
man and info files up to date.

The diff of bootstrap tree before and after the change:

    $ nix-store --query --graph $(nix-instantiate -A stdenv) |
        fgrep ' -> ' | awk '{print $3}' | sort -u |
        sed 's/"[0-9a-z]\{32\}-/"/g' | sort > before

    $ nix-store --query --graph $(nix-instantiate -A stdenv) |
        fgrep ' -> ' | awk '{print $3}' | sort -u |
        sed 's/"[0-9a-z]\{32\}-/"/g' | sort > after

    $ diff -U0 before after
    --- before
    +++ after
    @@ -100 +99,0 @@
    -"texinfo-6.8.drv"

Co-authored-by: Adam Joseph <54836058+amjoseph-nixpkgs@users.noreply.github.com>

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

@@ -15,7 +15,6 @@ in
 , noSysDirs
 , perl
 , substitute
-, texinfo
 , zlib
 
 , enableGold ? withGold stdenv.targetPlatform
@@ -52,7 +51,7 @@ let
   targetPrefix = lib.optionalString (targetPlatform != hostPlatform) "${targetPlatform.config}-";
 in
 
-stdenv.mkDerivation {
+stdenv.mkDerivation (finalAttrs: {
   pname = targetPrefix + "binutils";
   inherit version;
 
@@ -110,10 +109,12 @@ stdenv.mkDerivation {
 
   strictDeps = true;
   depsBuildBuild = [ buildPackages.stdenv.cc ];
+  # texinfo was removed here in https://github.com/NixOS/nixpkgs/pull/210132
+  # to reduce rebuilds during stdenv bootstrap.  Please don't add it back without
+  # checking the impact there first.
   nativeBuildInputs = [
     bison
     perl
-    texinfo
   ]
   ++ lib.optionals targetPlatform.isiOS [ autoreconfHook ]
   ++ lib.optionals buildPlatform.isDarwin [ autoconf269 automake gettext libtool ]
@@ -144,6 +145,20 @@ stdenv.mkDerivation {
     for i in binutils/Makefile.in gas/Makefile.in ld/Makefile.in gold/Makefile.in; do
         sed -i "$i" -e 's|ln |ln -s |'
     done
+
+    # autoreconfHook is not included for all targets.
+    # Call it here explicitly as well.
+    ${finalAttrs.postAutoreconf}
+  '';
+
+  postAutoreconf = ''
+    # As we regenerated configure build system tries hard to use
+    # texinfo to regenerate manuals. Let's avoid the dependency
+    # on texinfo in bootstrap path and keep manuals unmodified.
+    touch gas/doc/.dirstamp
+    touch gas/doc/asconfig.texi
+    touch gas/doc/as.1
+    touch gas/doc/as.info
   '';
 
   # As binutils takes part in the stdenv building, we don't want references
@@ -226,4 +241,4 @@ stdenv.mkDerivation {
     # collision due to the ld/as wrappers/symlinks in the latter.
     priority = 10;
   };
-}
+})