Merge pull request #277307 from helsinki-systems/fix/libao-pulseaudio

libao: Fix eval when config.pulseaudio is set

pkgs/top-level/all-packages.nix

···
   libagar_test = callPackage ../development/libraries/libagar/libagar_test.nix { };
 
   libao = callPackage ../development/libraries/libao {
-    usePulseAudio = config.pulseaudio or lib.meta.availableOn stdenv.hostPlatform libpulseaudio;
+    usePulseAudio = config.pulseaudio or (lib.meta.availableOn stdenv.hostPlatform libpulseaudio);
     inherit (darwin.apple_sdk.frameworks) CoreAudio CoreServices AudioUnit;
   };