Rebuild _freeze_importlib.o when Makefile changes
diff --git a/Makefile.pre.in b/Makefile.pre.in
index f2eb92a..2e04b27 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -688,7 +688,7 @@
 ############################################################################
 # Importlib
 
-Programs/_freeze_importlib.o: Programs/_freeze_importlib.c
+Programs/_freeze_importlib.o: Programs/_freeze_importlib.c Makefile
 
 Programs/_freeze_importlib: Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN)
 	$(LINKCC) $(PY_LDFLAGS) -o $@ Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)