Add a 'make reformat' rule.

Author: graydon

Makefile.in

@@ -240,3 +240,4 @@ include $(CFG_SRC_DIR)/mk/snap.mk
 include $(CFG_SRC_DIR)/mk/clean.mk
 include $(CFG_SRC_DIR)/mk/autodep.mk
 include $(CFG_SRC_DIR)/mk/fuzzer.mk
+include $(CFG_SRC_DIR)/mk/pp.mk

mk/pp.mk

@@ -0,0 +1,7 @@
+reformat: $(SREQ1)
+	@$(call E, reformat [stage1]: $@)
+	for i in $(wildcard $(addprefix $(S)src/comp/, \
+                          *.rs */*.rs */*/*.rs));  \
+    do $(call CFG_RUN_TARG,stage1, stage1/rustc$(X)) \
+       --pretty $$i >$$i.tmp && mv $$i.tmp $$i; \
+    done