make clean removes callbacks.exe from $ZIPR_INSTALL/bin

Makefile.in

@@ -12,6 +12,7 @@ all:
 	
 clean:
 	for i in ${dirs};  do cd $$i; make clean; cd ..; done
+	rm $(prefix)/bin/callbacks.exe
 
 install:
 	cp lib/callbacks.exe $(prefix)/bin/callbacks.exe