py/mkrules.mk: Add %.sz rule to print size of an object file.

It's frequently the case that a developer will want to compare the object
code size of various alternatives.  When this can be done at the single
object code level, the turnaround is faster.

Provide a rule `$(BUILD)/%.sz` to print the size of a given object.
Because it is a normal Makefile target that depends on an object file, it
rebuilds the object file if needed.

Signed-off-by: Jeff Epler <[email protected]>

Author: jepler

py/mkrules.mk

@@ -108,6 +108,10 @@ $(BUILD)/%.pp: %.c FORCE
 	$(ECHO) "PreProcess $<"
 	$(Q)$(CPP) $(CFLAGS) -Wp,-C,-dD,-dI -o $@ $<
 
+.PHONY: $(BUILD)/%.sz
+$(BUILD)/%.sz: $(BUILD)/%.o
+	$(Q)$(SIZE) $<
+
 # Special case for compiling auto-generated source files.
 $(BUILD)/%.o: $(BUILD)/%.c
 	$(call compile_c)