Update configure script to make the task-perf output directory.

Author: Eric Holk

configure

@@ -183,7 +183,7 @@ for i in \
     dl stage0 stage1 stage2 stage3 \
     stage0/lib stage1/lib stage2/lib stage3/lib \
     test/run-pass test/run-fail test/compile-fail \
-    test/bench/99-bottles test/bench/shootout
+    test/bench/99-bottles test/bench/shootout test/bench/task-perf
 do
     make_dir $i
 done