generate_extra_defs: Check for deprecated signals and properties
generate_extra_defs: Check for deprecated signals and properties

tools/extra_defs_gen/generate_extra_defs.cc: Mark deprecated signals and
properties as such in the generated .defs file.

GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm