t/curse: add a Makefile so we can compare speed when using GNU make.

redo: 5.4s
redo -j4: 3.0s
make: 2.3s
make -j4: 1.4s
make SHELL=/bin/dash: 1.2s
make SHELL=/bin/dash -j4: 0.83s

We have some distance to go yet.  Of course, redo is still written in
python, not C, so it's very expensive, and the on-disk dependency store is
very inefficient.

t/curse/Makefile

@@ -0,0 +1,26 @@
+all:
+	. ./check-1.sh
+	$(MAKE) 1.n0 2.n0 3.n0
+	$(MAKE) $(shell seq 10 | sed 's/$$/.n1/')
+	. ./check-2.sh
+
+%.n0: $(shell seq 10 | sed 's/$$/.n1/')
+	: >$@
+
+%.n1: $(shell seq 100 | sed 's/$$/.n2/')
+	echo n1-$* >$@
+
+.PRECIOUS: %.n2
+%.n2:
+	echo n2-$* >$@
+	echo $* >>$*.count
+	echo $* >>in.countall
+	$(MAKE) countall
+
+.PHONY: countall
+countall:
+	echo $@ >>out.countall
+	echo hello >$@
+
+clean:
+	rm -f *~ .*~ *.n0 *.n1 *.n2 *.tmp *.count countall *.countall