musescore: build in release configuration

This affects settings and document directories.

The configuration was "release" before the switch from fetchzip to
fetchFromGitHub.

pkgs/applications/audio/musescore/default.nix

@@ -21,6 +21,7 @@ mkDerivation rec {
   ];
 
   cmakeFlags = [
+    "-DMUSESCORE_BUILD_CONFIG=release"
     "-DUSE_SYSTEM_FREETYPE=ON"
   ];