Add empty targets for dependencies in sub make file

This forces make to check if dependency (eg ../Common/Common.a) is more
recent than the target

RemoteControl/Makefile

@@ -4,7 +4,7 @@ OBJECTS = RemoteControlAppD.o RemoteControlCallsignData.o RemoteControlConfig.o
 .PHONY: all
 all:		remotecontrold
 
-remotecontrold:	$(OBJECTS)
+remotecontrold:	$(OBJECTS) ../Common/Common.a
 		$(CXX) $(OBJECTS) ../Common/Common.a $(LDFLAGS) $(LIBS) -o remotecontrold
 
 -include $(OBJECTS:.o=.d)
@@ -21,3 +21,4 @@ install:
 clean:
 		$(RM) remotecontrold *.o *.d *.bak *~
 
+../Common/Common.a:

RemoteControl/MakefileGUI

@@ -5,7 +5,7 @@ OBJECTS = RemoteControlApp.o RemoteControlCallsignData.o RemoteControlConfig.o R
 .PHONY: all
 all:		remotecontrol
 
-remotecontrol:	$(OBJECTS)
+remotecontrol:	$(OBJECTS) ../GUICommon/GUICommon.a ../Common/Common.a
 		$(CXX) $(OBJECTS) ../GUICommon/GUICommon.a ../Common/Common.a $(LDFLAGS) $(GUILIBS) -o remotecontrol
 
 -include $(OBJECTS:.o=.d)
@@ -22,3 +22,5 @@ install:
 clean:
 		$(RM) remotecontrol *.o *.d *.bak *~
 
+../GUICommon/GUICommon.a:
+../Common/Common.a: