Improve 'clean' make target.

Makefile.in

@@ -1014,8 +1014,8 @@ tidy:
 
 clean:
 	@$(call E, cleaning)
-	$(Q)rm -f $(RUNTIME_OBJS)
-	$(Q)rm -f $(RUSTLLVM_OBJS)
+	$(Q)rm -f $(RUNTIME_OBJS) $(RUNTIME_DEF)
+	$(Q)rm -f $(RUSTLLVM_OBJS) $(RUSTLLVM_DEF)
 	$(Q)rm -f $(BOOT_CMOS) $(BOOT_CMIS) $(BOOT_CMXS) $(BOOT_OBJS)
 	$(Q)rm -f $(ML_DEPFILES) $(C_DEPFILES) $(CRATE_DEPFILES)
 	$(Q)rm -f $(ML_DEPFILES:%.d=%.d.tmp)
@@ -1030,6 +1030,7 @@ clean:
 	$(Q)rm -Rf $(PKG_NAME)-*.tar.gz dist
 	$(Q)rm -f $(foreach ext,cmx cmi cmo cma bc o a d exe,\
                         $(wildcard boot/*/*.$(ext) boot/*/*/*.$(ext)))
+	$(Q)rm -f $(foreach ext,o a d bc s exe,$(wildcard stage*/*.$(ext)))
 	$(Q)rm -Rf $(foreach ext,out out.tmp                               \
                              boot$(X) stage0$(X) stage1$(X) stage2$(X) \
                              bc o s exe dSYM,                          \