Fix namespace for GObject introspection
The following warnings were fixed:
libxfce4ui-config.h:80: Warning: Libxfce4ui: symbol='libxfce4ui_check_version': Unknown namespace for symbol 'libxfce4ui_check_version' libxfce4ui-config.h:38: Warning: Libxfce4ui: symbol='LIBXFCE4UI_MAJOR_VERSION': Unknown namespace for symbol 'LIBXFCE4UI_MAJOR_VERSION' libxfce4ui-config.h:47: Warning: Libxfce4ui: symbol='LIBXFCE4UI_MINOR_VERSION': Unknown namespace for symbol 'LIBXFCE4UI_MINOR_VERSION' libxfce4ui-config.h:56: Warning: Libxfce4ui: symbol='LIBXFCE4UI_MICRO_VERSION': Unknown namespace for symbol 'LIBXFCE4UI_MICRO_VERSION' libxfce4ui-config.h:68: Warning: Libxfce4ui: symbol='LIBXFCE4UI_CHECK_VERSION': Unknown namespace for symbol 'LIBXFCE4UI_CHECK_VERSION'
These warnings were produced while running g-ir-scanner.
Libxfce4ui version check was skipped from generated .gir because of this.