screen FTBFS if make uses parallel building (at least with -j8). This
patch adds the missing dependencies to make parallel builds work, too.

Index: screen-4.1.0~20120320gitdb59704/Makefile.in
===================================================================
--- screen-4.1.0~20120320gitdb59704.orig/Makefile.in	2012-06-10 17:35:56.616100993 +0200
+++ screen-4.1.0~20120320gitdb59704/Makefile.in	2012-06-10 17:40:37.784352971 +0200
@@ -350,7 +350,7 @@
 viewport.o: layout.h viewport.h canvas.h viewport.c config.h screen.h os.h osdef.h ansi.h acls.h \
  comm.h layer.h term.h image.h display.h window.h extern.h \
  braille.h
-list_generic.o: list_generic.h list_generic.c layer.h
-list_display.o: list_generic.h list_display.c layer.h
-list_window.o: list_generic.h list_window.c window.h layer.h
+list_generic.o: list_generic.h list_generic.c layer.h screen.h osdef.h
+list_display.o: list_generic.h list_display.c layer.h screen.h osdef.h
+list_window.o: list_generic.h list_window.c window.h layer.h screen.h osdef.h