dbus: fix install name on installed binaries

Some binaries have incorrect install names. They should be the absolute
path, but they have `@rpath` instead. This something that Meson should
handle automatically, but it’s not happening for these binaries.

pkgs/by-name/db/dbus/package.nix

@@ -156,6 +156,14 @@ stdenv.mkDerivation (finalAttrs: {
       --replace-fail 'DBUS_DAEMONDIR"/dbus-daemon"' '"/run/current-system/sw/bin/dbus-daemon"'
   '';
 
+  postInstall = lib.optionalString stdenv.hostPlatform.isDarwin ''
+    # For some reason, only these binaries reference the dylib by rpath instead of by an absolute install name.
+    for exe in bin/dbus-daemon bin/dbus-run-session libexec/dbus-daemon-launch-helper; do
+      install_name_tool "$out/$exe" \
+        -change "@rpath/libdbus-1.3.dylib" "$lib/lib/libdbus-1.3.dylib"
+    done
+  '';
+
   postFixup = ''
     # It's executed from $lib by absolute path
     moveToOutput bin/dbus-launch "$lib"