gtk4: fix build on darwin by linking with lld (#541749)

pkgs/by-name/gt/gtk4/package.nix

@@ -60,6 +60,7 @@
   compileSchemas ? stdenv.hostPlatform.emulatorAvailable buildPackages,
   cups,
   libexecinfo,
+  llvmPackages,
   broadwaySupport ? true,
   testers,
   darwinMinVersionHook,
@@ -130,6 +131,10 @@ stdenv.mkDerivation (finalAttrs: {
   ++ lib.optionals vulkanSupport [
     shaderc # for glslc
   ]
+  ++ lib.optionals stdenv.hostPlatform.isDarwin [
+    # TODO: Remove when NixOS/nixpkgs#536365 reaches master.
+    llvmPackages.lld
+  ]
   ++ finalAttrs.setupHooks;
 
   buildInputs = [
@@ -221,6 +226,10 @@ stdenv.mkDerivation (finalAttrs: {
   }
   // lib.optionalAttrs stdenv.hostPlatform.isMusl {
     NIX_LDFLAGS = "-lexecinfo";
+  }
+  // lib.optionalAttrs stdenv.hostPlatform.isDarwin {
+    # TODO: Remove when NixOS/nixpkgs#536365 reaches master.
+    NIX_CFLAGS_LINK = "--ld-path=${lib.getExe' llvmPackages.lld "ld64.lld"}";
   };
 
   postPatch = ''