Sign executables after patching revision on Darwin

#1580 introduced patching of
resulting binary in a separate derivation that ends up with bad
(or missing) code signature which prevents it from running:

   % nix run
  zsh: killed     nix run

and Console.app revealing the reason:

  Exception Type:        EXC_BAD_ACCESS (SIGKILL (Code Signature Invalid))
  Exception Codes:       UNKNOWN_0x32 at 0x00000001054e4199
  Exception Codes:       0x0000000000000032, 0x00000001054e4199

This change uses autoSignDarwinBinariesHook to sign the result that
seems to fix the problem.

flake.nix

@@ -232,9 +232,12 @@
         pname = pkg.pname + "-rev-fixup";
         inherit (pkg) version meta;
         src = pkg;
-        buildInputs = [ pkgs.bbe ];
+        buildInputs = [ pkgs.bbe ]
+          ++ pkgs.lib.optionals pkgs.stdenv.isDarwin [ pkgs.darwin.autoSignDarwinBinariesHook ];
         phases = [ "fixupPhase" ];
         fixupPhase = ''
+          runHook preFixup
+
           mkdir -p $out/bin
           for srcBin in $src/bin/*; do
             outBin="$out/bin/$(basename $srcBin)"
@@ -245,6 +248,8 @@
               $srcBin > $outBin
             chmod +x $outBin
           done
+
+          runHook postFixup
         '';
       };