tools/emul: add "make rescue" command

tools/emul/Makefile

@@ -47,6 +47,15 @@ updatebootstrap: $(ZASMBIN)
 	$(ZASMBIN) < zasm/glue.asm > zasm/kernel.bin
 	$(ZASMBIN) < $(APPS)/zasm/glue.asm > zasm/zasm.bin
 
+# Sometimes, when developing zasm, stuff get messed up and it's hard to unmess
+# because zasm's brake-up ends up in its bootstrap bins. Sure, we can revert
+# from git, but if we're in the middle of some work, it's inconvenient. As long
+# as we don't diverge from scas's syntax, it can come to the recue!
+.PHONY: rescue
+rescue:
+	scas -o zasm/kernel.bin -I $(KERNEL) zasm/glue.asm
+	scas -o zasm/zasm.bin -I $(APPS) $(APPS)/zasm/glue.asm
+
 .PHONY: clean
 clean:
 	rm -f $(TARGETS) zasm/{kernel,user}.h shell/kernel.h zasm/includes.*