patch 8.2.0622: Haiku: GUI does not compile

Problem:    Haiku: GUI does not compile.
Solution:   Various fixes. (Emir Sari, closes #5961)
diff --git a/src/Makefile b/src/Makefile
index b110f91..19453c7 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1404,8 +1404,8 @@
 HAIKUGUI_BUNDLE =
 
 # All GUI files
-ALL_GUI_SRC  = gui.c gui_gtk.c gui_gtk_f.c gui_motif.c gui_xmdlg.c gui_xmebw.c gui_athena.c gui_gtk_x11.c gui_x11.c gui_at_sb.c gui_at_fs.c
-ALL_GUI_PRO  = gui.pro gui_gtk.pro gui_motif.pro gui_xmdlg.pro gui_athena.pro gui_gtk_x11.pro gui_x11.pro gui_w32.pro gui_photon.pro
+ALL_GUI_SRC  = gui.c gui_gtk.c gui_gtk_f.c gui_motif.c gui_xmdlg.c gui_xmebw.c gui_athena.c gui_gtk_x11.c gui_x11.c gui_at_sb.c gui_at_fs.c gui_haiku.cc
+ALL_GUI_PRO  = gui.pro gui_gtk.pro gui_motif.pro gui_xmdlg.pro gui_athena.pro gui_gtk_x11.pro gui_x11.pro gui_w32.pro gui_photon.pro gui_haiku.pro
 
 # }}}