[gtkmm/gtkmm-3-24] (10 commits) ...Merge branch 'use-dllexport-3-24' into 'gtkmm-3-24'

[Chun-wei Fan <fanchunwei src gnome org>]

Summary of changes:

  735c661... gdk/gdkmmconfig.h.in: Add GDKMM_API (*)
  a4026ce... gtk/gtkmmconfig.h.in: Re-organize GTKMM_API definitions (*)
  6a18b21... gdk/src/*.hg: Mark classes and functions with GDKMM_API (*)
  2acdb83... gdk/gdkmm/*.h: Mark functions with GDKMM_API (*)
  d0a9ad2... tools/m4/class_gtkobject.m4: Allow applying decorations (*)
  c123cf9... gtk/src/*.hg: Mark classes and functions with GTKMM_API (*)
  7cbbca9... gtk/gtkmm/*.h: Mark functions with GTKMM_API (*)
  6feac83... NMake Makefiles: Export symbols without gendef if possible (*)
  703c980... NMake Makefiles: Ignore warning C4273 (*)
  3d0068b... Merge branch 'use-dllexport-3-24' into 'gtkmm-3-24'

(*) This commit already existed in another branch; no separate mail sent