qtwebengine: link to pulseaudio

Nix builds of QTWebEngine doesn't support sound output via Pulse, only
through ALSA, unless sandboxing is disabled and LD_LIBRARY_PATH
contains a reference to the Pulse libraries.

By default, Chromium won't link to PulseAudio, but dlopens it in
run-time. It is tricky to make this work because of the nontrivial
sandbox configuration. Nix builds of Chromium already link against
Pulse directly, so it makes sense to copy this behavior in
QTWebEngine.

pkgs/development/libraries/qt-5/5.15/default.nix

@@ -170,6 +170,7 @@ let
         extraPrefix = "src/3rdparty/";
         hash = "sha256-s4GsGMJTBNWw2gTJuIEP3tqT82AmTsR2mbj59m2p6rM=";
       })
+      ./qtwebengine-link-pulseaudio.patch
     ] ++ lib.optionals stdenv.isDarwin [
       ./qtwebengine-darwin-no-platform-check.patch
       ./qtwebengine-mac-dont-set-dsymutil-path.patch

pkgs/development/libraries/qt-5/5.15/qtwebengine-link-pulseaudio.patch

@@ -0,0 +1,8 @@
+--- a/src/core/config/common.pri
++++ b/src/core/config/common.pri
+@@ -47,3 +47,5 @@
+
+ !qtConfig(webengine-nodejs10): gn_args += use_rollup=false
+ gn_args += enable_ipc_logging=false
++
++gn_args += link_pulseaudio=true

pkgs/development/libraries/qt-6/modules/qtwebengine.nix

@@ -135,6 +135,7 @@ qtModule {
     # environment variable, since NixOS relies on it working.
     # See https://github.com/NixOS/nixpkgs/issues/226484 for more context.
     ../patches/qtwebengine-xkb-includes.patch
+    ../patches/qtwebengine-link-pulseaudio.patch
   ];
 
   postPatch = ''

pkgs/development/libraries/qt-6/patches/qtwebengine-link-pulseaudio.patch

@@ -0,0 +1,10 @@
+--- a/src/core/CMakeLists.txt
++++ b/src/core/CMakeLists.txt
+@@ -341,6 +341,7 @@
+             devtools_fast_bundle=false
+             devtools_skip_typecheck=false
+             enable_jxl_decoder=false # temporarily because libjxl causes internal compiler error on armv7
++            link_pulseaudio=true
+         )
+
+         extend_gn_list(gnArgArg