* gtk/src/assistant.ccg: Add extern "C".
* gtk/src/buildable.[ccg|hg]:
Call Buildable_Class::custom_tag_[start|end]_vfunc_callback()
via local functions with C linkage.
* gtk/src/builderscope.[ccg|hg]:
Call BuilderScope_Class::get_type_from_name_vfunc_callback()
via a local function with C linkage.
* gtk/src/cellarea.ccg:
* gtk/src/celllayout.ccg:
* gtk/src/cssprovider.ccg: Add extern "C".
* gtk/src/drawingarea.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotDraw>.
* gtk/src/entrycompletion.ccg:
* gtk/src/iconview.ccg: Add extern "C".
* gtk/src/menubutton.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotCreatePopup>.
* gtk/src/printer.ccg: Add extern "C".
* gtk/src/printjob.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotPrintJobComplete>.
* gtk/src/printoperation.ccg:
* gtk/src/printsettings.ccg: Add extern "C".
* gtk/src/scale.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotFormatValue>.
* gtk/src/shortcutaction.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotShortcut>.
* gtk/src/textiter.ccg:
* gtk/src/texttagtable.ccg: Add extern "C".
* gtk/src/treelistmodel.ccg: Add extern "C". Use a local function with
C linkage instead of Glib::destroy_notify_delete<SlotCreateModel>.
* gtk/src/treemodel.[ccg|hg]:
Call TreeModel_Class::iter_next_vfunc_callback() and 5 other vfuncs
via local functions with C linkage.
* gtk/src/treemodelfilter.ccg:
* gtk/src/treeselection.ccg:
* gtk/src/treesortable.ccg: Add extern "C".
* gtk/src/widget.[ccg|hg]: Add extern "C".
Call Widget_Class::dispose_vfunc_callback() via a local function
with C linkage. Use a local function with C linkage instead of
Glib::destroy_notify_delete<SlotTick>.
* gtk/src/window.[ccg|hg]: Call Window_Class::dispose_vfunc_callback()
via a local function with C linkage.