Allow multiple shells to be enabled.

Makefile

@@ -349,7 +349,7 @@ busybox.links: busybox.mkll Config.h applets.h
 	- $(SHELL) $^ >$@
 
 nfsmount.o cmdedit.o: %.o: %.h
-sh.o: cmdedit.h
+ash.o hush.o lash.o msh.o: cmdedit.h
 $(OBJECTS): %.o: %.c Config.h busybox.h applets.h Makefile
 	$(CC) $(CFLAGS) -I. $(patsubst %,-I%,$(subst :, ,$(BB_SRC_DIR))) -c $< -o $*.o
 
@@ -377,8 +377,6 @@ libbb.a:  $(LIBBB_MOBJ) $(LIBBB_AROBJS) $(LIBBB_OBJS)
 
 usage.o: usage.h
 
-sh.o: sh.c lash.c hush.c msh.c ash.c
-
 libbb/loop.o: libbb/loop.h
 
 libbb/loop.h: mk_loop_h.sh