nova: Fix source file names in Makefile homework bundle targets

nova/Makefile

@@ -32,10 +32,10 @@ cla cleanall : clean
 	make -C kern/build cleanall
 
 hw10 :
-	zip hw10.zip kern/src/ec_syscall.cc
+	zip osy-hw10.zip kern/src/ec_syscall.cc
 
 hw11 :
-	zip hw11.zip kern/src/ec_syscall.cc $(or $(wildcard user/mem_alloc.cc),user/mem_alloc.c)
+	zip osy-hw11.zip kern/src/ec_syscall.cc $(or $(wildcard user/mem_alloc.cc),user/mem_alloc.c)
 
 hw12 :
-	zip hw12.zip kern/scr/ec_syscall.cc kern/scr/context_construct.cc kern/include/ec.h
+	zip osy-hw12.zip kern/src/ec_syscall.cc