(clean): Use OBJDIR macro.

lib-src/makefile.nt

@@ -202,7 +202,7 @@ install:	$(INSTALL_FILES)
 # 
 clean:;		- $(DEL) *~ *.pdb DOC*
 		- $(DEL_TREE) deleted
-		- $(DEL_TREE) obj
+		- $(DEL_TREE) $(OBJDIR)
 
 #
 # Headers we would preprocess if we could.

nt/makefile.nt

@@ -142,7 +142,7 @@ real_install:
 CLEAN_CMD	= $(MAKE) -f makefile.nt clean
 clean:;		- $(DEL) *~ *.pdb
 		- $(DEL_TREE) deleted
-		- $(DEL_TREE) obj
+		- $(DEL_TREE) $(OBJDIR)
 		- $(DEL_TREE) ..\bin
 		- $(DEL) ..\etc\DOC ..\etc\DOC-X
 		- $(DEL) emacs.bat