build: disable LTO on Darwin

Due to https://git.lix.systems/lix-project/lix/issues/832 , Lix 2.93.0
fails to build on Darwin without overrides. Until the root cause has
been determined and fixed, build without LTO.

Change-Id: I4db5eb294d8f19e5a366b1e19efa5a327b3e2e78

package.nix

@@ -264,6 +264,8 @@ stdenv.mkDerivation (finalAttrs: {
       (lib.mesonBool "werror" werror)
     ]
     ++ lib.optional (hostPlatform != buildPlatform) "--cross-file=${mesonCrossFile}"
+    # Temporary workaround for https://git.lix.systems/lix-project/lix/issues/832
+    ++ lib.optional (hostPlatform.isDarwin) "-Db_lto=false"
     ++ sanitizeOpts;
 
   # We only include CMake so that Meson can locate toml11, which only ships CMake dependency metadata.