Author: Fabio Fantoni <fantonifabio@tiscali.it>
Description: meson: remove unknown arguments that cause fail to build

The build was failing with:
retro-gtk/meson.build:188:4:
ERROR: Got unknown keyword arguments "export_packages", "namespace"

Checking https://mesonbuild.com/Pkgconfig-module.html the arguments
"export_packages" and "namespace" are not present in pkg.generate, so
I removed them to make the build complete

Forwarded: not yet
---
--- a/retro-gtk/meson.build
+++ b/retro-gtk/meson.build
@@ -189,8 +189,6 @@
     description: 'A simple GObject game controller library',
       libraries: retro_gtk_lib,
            name: 'retro-gtk',
-      namespace: 'Retro',
-export_packages: 'retro-gtk',
        filebase: 'retro-gtk-' + retro_gtk_api_version,
         version: meson.project_version(),
         subdirs: 'retro-gtk',