Make syntex's makefile like most other makefiles.

nnethercote · nnethercote · commit d0cd62c6c34f · 2016-09-28T13:47:53.000+10:00
This benchmark doesn't need any special handling, so it's makefile
might as well be identical to the other non-special benchmarks'
makefiles.
diff --git a/syntex-0.42.2/makefile b/syntex-0.42.2/makefile
@@ -1,8 +1,7 @@
 all:
 	$(CARGO_BUILD)
-
 touch:
-	cargo clean
-
+	rm -rf target/debug/*
 clean:
-	cargo clean
+	rm target -rf
+	rm Cargo.lock
