[src] Make sure dlls have their timestamps updated after attempting to build them. (#426)

This tries to work around a make bug where make gets confused and ends
up in an infinite loop if a executing a target (because one of the dependencies
changed) does not actually change the timestamp of the target (while this is logically
unsound, it can certainly happen when invoking submakes to build stuff because
the supermake does not have a complete knowledge about all the dependencies
(because our makefiles aren't perfect)).

src/Makefile

@@ -203,9 +203,11 @@ $(IOS_BUILD_DIR)/reference/Xamarin.iOS.dll.mdb: $(IOS_BUILD_DIR)/reference/Xamar
 
 $(MONO_PATH)/mcs/class/lib/monotouch/compat_Facades/System.Drawing.Primitives.dll: $(IOS_BUILD_DIR)/compat/monotouch.dll
 	$(call Q_PROF_MCS,ios/compat) $(MAKE) $(if $(V),,-s) -C $(MONO_PATH)/mcs/class/Facades/System.Drawing.Primitives PROFILE=monotouch LIBRARY_SUBDIR=compat_Facades    EXTRA_LIB_MCS_FLAGS="-r:$(abspath $(IOS_BUILD_DIR)/compat/monotouch.dll)"
+	@touch $@
 
 $(MONO_PATH)/mcs/class/lib/monotouch/reference_Facades/System.Drawing.Primitives.dll: $(IOS_BUILD_DIR)/reference/Xamarin.iOS.dll
 	$(call Q_PROF_MCS,ios/unified) $(MAKE) $(if $(V),,-s) -C $(MONO_PATH)/mcs/class/Facades/System.Drawing.Primitives PROFILE=monotouch LIBRARY_SUBDIR=reference_Facades EXTRA_LIB_MCS_FLAGS="-r:$(abspath $(IOS_BUILD_DIR)/reference/Xamarin.iOS.dll)"
+	@touch $@
 
 $(IOS_BUILD_DIR)/%/Facades/System.Drawing.Primitives.dll: $(MONO_PATH)/mcs/class/lib/monotouch/%_Facades/System.Drawing.Primitives.dll | $(IOS_BUILD_DIR)/compat/Facades $(IOS_BUILD_DIR)/reference/Facades
 	$(Q) cp $< $@
@@ -528,6 +530,7 @@ $(MAC_BUILD_DIR)/%-reference/Xamarin.Mac.dll: $(MAC_BUILD_DIR)/%-64/Xamarin.Mac.
 
 $(MONO_PATH)/mcs/class/lib/xammac/reference_Facades/System.Drawing.Primitives.dll: $(MAC_BUILD_DIR)/mobile-reference/Xamarin.Mac.dll
 	$(call Q_PROF_MCS,xammac) $(MAKE) $(if $(V),,-s) -C $(MONO_PATH)/mcs/class/Facades/System.Drawing.Primitives PROFILE=xammac LIBRARY_SUBDIR=reference_Facades EXTRA_LIB_MCS_FLAGS="-r:$(abspath $(MAC_BUILD_DIR)/mobile-reference/Xamarin.Mac.dll)"
+	@touch $@
 
 $(MAC_BUILD_DIR)/mobile/Facades/System.Drawing.Primitives.dll: $(MONO_PATH)/mcs/class/lib/xammac/reference_Facades/System.Drawing.Primitives.dll $(MAC_BUILD_DIR)/mobile/Facades 
 	$(Q) cp $< $@
@@ -985,6 +988,7 @@ $(TVOS_BUILD_DIR)/reference/MonoTouch.Dialog-1.dll: $(TVOS_BUILD_DIR)/reference/
 
 $(MONO_PATH)/mcs/class/lib/monotouch_tv/reference_Facades/System.Drawing.Primitives.dll: $(TVOS_BUILD_DIR)/reference/Xamarin.TVOS.dll
 	$(call Q_PROF_MCS,tvos) $(MAKE) $(if $(V),,-s) -C $(MONO_PATH)/mcs/class/Facades/System.Drawing.Primitives PROFILE=monotouch_tv LIBRARY_SUBDIR=reference_Facades EXTRA_LIB_MCS_FLAGS="-r:$(abspath $(TVOS_BUILD_DIR)/reference/Xamarin.TVOS.dll)"
+	@touch $@
 
 $(TVOS_BUILD_DIR)/%/Facades/System.Drawing.Primitives.dll: $(MONO_PATH)/mcs/class/lib/monotouch_tv/%_Facades/System.Drawing.Primitives.dll | $(TVOS_BUILD_DIR)/reference/Facades
 	$(Q) cp $< $@