mimetic: fix compilation failure with new toolchain

pkgs/development/libraries/mimetic/default.nix

···
-{ lib, stdenv, fetchurl, cutee }:
+{ lib, stdenv, fetchurl, fetchpatch, cutee }:
 
 stdenv.mkDerivation rec {
   pname = "mimetic";
···
 
   buildInputs = [ cutee ];
 
-  patches = lib.optional stdenv.isAarch64 ./narrowing.patch;
+  patches = [
+    # Fix build with gcc11
+    (fetchpatch {
+      url = "https://github.com/tat/mimetic/commit/bf84940f9021950c80846e6b1a5f8b0b55991b00.patch";
+      sha256 = "sha256-1JW9zPg67BgNsdIjK/jp9j7QMg50eRMz5FsDsbbzBlI=";
+    })
+  ] ++ lib.optional stdenv.isAarch64 [ ./narrowing.patch ];
 
   meta = with lib; {
     description = "MIME handling library";