install fix (Rusty Russel)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@685 c046a42c-6fe2-441c-8c8c-71466251a162

Makefile.target

@@ -302,7 +302,9 @@ clean:
 	rm -f *.o  *.a *~ $(PROGS) gen-op.h opc.h op.h nwfpe/*.o
 
 install: all 
+ifneq ($(PROGS),)
 	install -m 755 -s $(PROGS) $(prefix)/bin
+endif
 
 ifneq ($(wildcard .depend),)
 include .depend