tests.pkgs-lib: Fix for darwin

pkgs/pkgs-lib/formats/java-properties/test/default.nix

@@ -77,7 +77,8 @@ stdenv.mkDerivation {
   src = lib.sourceByRegex ./. [
     ".*\.java"
   ];
-  LANG = "C.UTF-8";
+  # On Linux, this can be C.UTF-8, but darwin + zulu requires en_US.UTF-8
+  LANG = "en_US.UTF-8";
   buildPhase = ''
     javac Main.java
   '';