llvm: move LDFLAGS into env for structuredAttrs

pkgs/development/compilers/llvm/common/lld/default.nix

@@ -64,7 +64,9 @@ stdenv.mkDerivation (finalAttrs: {
   ++ devExtraCmakeFlags;
 
   # Musl's default stack size is too small for lld to be able to link Firefox.
-  LDFLAGS = lib.optionalString stdenv.hostPlatform.isMusl "-Wl,-z,stack-size=2097152";
+  env = lib.optionalAttrs stdenv.hostPlatform.isMusl {
+    LDFLAGS = "-Wl,-z,stack-size=2097152";
+  };
 
   outputs = [
     "out"

pkgs/development/compilers/llvm/common/llvm/default.nix

@@ -453,9 +453,9 @@ stdenv.mkDerivation (
       '';
 
     # E.g. Mesa uses the build-id as a cache key (see #93946):
-    LDFLAGS = optionalString (
-      enableSharedLibraries && !stdenv.hostPlatform.isDarwin
-    ) "-Wl,--build-id=sha1";
+    env = lib.optionalAttrs (enableSharedLibraries && !stdenv.hostPlatform.isDarwin) {
+      LDFLAGS = "-Wl,--build-id=sha1";
+    };
 
     cmakeBuildType = "Release";