birdtray: fix qttranslations path birdtray crashes not finding the translations without this fix

pkgs/applications/misc/birdtray/default.nix

···
   , qtbase
   , qttools
   , qtx11extras
+  , qttranslations
 }:
 
 mkDerivation rec {
···
     rev = version;
     sha256 = "15l8drdmamq1dpqpj0h9ajj2r5vcs23cx421drvhfgs6bqlzd1hl";
   };
+
+  patches = [
+    # See https://github.com/NixOS/nixpkgs/issues/86054
+    ./fix-qttranslations-path.diff
+  ];
 
   nativeBuildInputs = [ cmake pkgconfig ];
   buildInputs = [
     qtbase qttools qtx11extras
   ];
+
+  postPatch = ''
+    substituteInPlace src/birdtrayapp.cpp \
+      --subst-var-by qttranslations ${qttranslations}
+  '';
 
   meta = with lib; {
     description = "Mail system tray notification icon for Thunderbird";

pkgs/applications/misc/birdtray/fix-qttranslations-path.diff

···
+diff --git a/src/birdtrayapp.cpp b/src/birdtrayapp.cpp
+index 847b4d3..3a3709a 100644
+--- a/src/birdtrayapp.cpp
++++ b/src/birdtrayapp.cpp
+@@ -130,7 +130,7 @@ bool BirdtrayApp::loadTranslations() {
+             [](QString path) { return path.append("/translations"); });
+     QLocale locale = QLocale::system();
+     bool success = loadTranslation(
+-            qtTranslator, locale, "qt", {QLibraryInfo::location(QLibraryInfo::TranslationsPath)});
++            qtTranslator, locale, "qt", {QLatin1String("@qttranslations@/translations")});
+     success &= loadTranslation(dynamicTranslator, locale, "dynamic", locations);
+     success &= loadTranslation(mainTranslator, locale, "main", locations);
+     return success;