Allow toggling antialiasing inside the Haiku font dialog

Allow toggling antialiasing inside the Haiku font dialog

* src/haiku_support.cc (struct font_selection_dialog_message):
New field `disable_antialias'.
(MessageReceived): Handle new message SET_DISABLE_ANTIALIASING.
(class DualLayoutView): Rename to `TripleLayoutView'.
(class TripleLayoutView): Rename from `DualLayoutView'.
(MinSize): Update computations for three views.

(class EmacsFontSelectionDialog, UpdatePreview)
(EmacsFontSelectionDialog): Add an antialiasing checkbox to
control antialiasing.
(be_select_font): New arguments `initial_antialias' and
`disable_antialias'.

* src/haiku_support.h: Update prototypes.

* src/haikufont.c (haikufont_pattern_from_object): Set
FSPEC_ANTIALIAS.
(Fx_select_font): Update accordingly.