libfive: revert eigen to fix build (#386914)

pkgs/development/libraries/libfive/default.nix

@@ -3,6 +3,8 @@
   stdenv,
   wrapQtAppsHook,
   fetchFromGitHub,
+  fetchFromGitLab,
+  fetchpatch,
   unstableGitUpdater,
   cmake,
   ninja,
@@ -36,7 +38,32 @@ stdenv.mkDerivation {
     python.pkgs.pythonImportsCheckHook
   ];
   buildInputs = [
-    eigen
+    # reverts 'eigen: 3.4.0 -> 3.4.0-unstable-2022-05-19'
+    # https://github.com/nixos/nixpkgs/commit/d298f046edabc84b56bd788e11eaf7ed72f8171c
+    (eigen.overrideAttrs (old: rec {
+      version = "3.4.0";
+      src = fetchFromGitLab {
+        owner = "libeigen";
+        repo = "eigen";
+        rev = version;
+        hash = "sha256-1/4xMetKMDOgZgzz3WMxfHUEpmdAm52RqZvz6i0mLEw=";
+      };
+      patches = (old.patches or [ ]) ++ [
+        # Fixes e.g. onnxruntime on aarch64-darwin:
+        # https://hydra.nixos.org/build/248915128/nixlog/1,
+        # originally suggested in https://github.com/NixOS/nixpkgs/pull/258392.
+        #
+        # The patch is from
+        # ["Fix vectorized reductions for Eigen::half"](https://gitlab.com/libeigen/eigen/-/merge_requests/699)
+        # which is two years old,
+        # but Eigen hasn't had a release in two years either:
+        # https://gitlab.com/libeigen/eigen/-/issues/2699.
+        (fetchpatch {
+          url = "https://gitlab.com/libeigen/eigen/-/commit/d0e3791b1a0e2db9edd5f1d1befdb2ac5a40efe0.patch";
+          hash = "sha256-8qiNpuYehnoiGiqy0c3Mcb45pwrmc6W4rzCxoLDSvj0=";
+        })
+      ];
+    }))
     zlib
     libpng
     boost