libretro.citra: fix compilation

pkgs/misc/emulators/retroarch/cores.nix

···
 , cmake
 , curl
 , fetchFromGitHub
-, fetchgit
 , fetchpatch
 , ffmpeg
 , fluidsynth
···
 
   citra = mkLibRetroCore rec {
     core = "citra";
-    src = getCoreSrc core;
+    # `nix-prefetch-github` doesn't support `deepClone`, necessary for citra
+    # https://github.com/seppeljordan/nix-prefetch-github/issues/41
+    src = fetchFromGitHub {
+      inherit (hashesFile.citra) owner repo rev fetchSubmodules;
+      deepClone = true;
+      sha256 = "sha256-bwnYkMvbtRF5bGZRYVtMWxnCu9P45qeX4+ntOj9eRds=";
+    };
     description = "Port of Citra to libretro";
     license = gpl2Plus;
     extraNativeBuildInputs = [ cmake pkg-config ];