linux/manual-config: Move configfile symlinking to configurePhase.

It makes more semantic sense there than in unpackPhase, as that symlink is _how_ we configure the kernel

pkgs/os-specific/linux/kernel/manual-config.nix

@@ -112,12 +112,12 @@ stdenv.mkDerivation {
   unpackPhase = ''
     mkdir build
     export buildRoot="$(pwd)/build"
-    ln -sv ${configfile} $buildRoot/.config
     cd $sourceRoot
   '';
 
   configurePhase = ''
     runHook preConfigure
+    ln -sv ${configfile} $buildRoot/.config
     make $makeFlags "''${makeFlagsArray[@]}" oldconfig
     runHook postConfigure
   '';