caffeine: fix darwin build (#540764)

pkgs/by-name/ca/caffeine/package.nix

@@ -5,6 +5,7 @@
   apple-sdk,
   darwin,
   xcbuildHook,
+  llvmPackages,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -31,6 +32,8 @@ stdenv.mkDerivation (finalAttrs: {
   nativeBuildInputs = [
     xcbuildHook
     darwin.autoSignDarwinBinariesHook
+    # TODO: Remove once #536365 reaches this branch
+    llvmPackages.lld
   ];
 
   buildInputs = [
@@ -42,6 +45,9 @@ stdenv.mkDerivation (finalAttrs: {
     "-configuration Release"
   ];
 
+  # TODO: Remove once #536365 reaches this branch
+  env.NIX_CFLAGS_LINK = "-fuse-ld=lld";
+
   installPhase = ''
     runHook preInstall