Let the CFI test communicate via stdout rather than arbitrary sleep.

I suspect the gcstress test might have been flaky due to the sleep not
being long enough and I would like to avoid just arbitrarily increasing it.

Change-Id: I5d4e0be35aa9f48b66167df04b8a539b21787053
diff --git a/test/137-cfi/cfi.cc b/test/137-cfi/cfi.cc
index 87656bc..45251b8 100644
--- a/test/137-cfi/cfi.cc
+++ b/test/137-cfi/cfi.cc
@@ -53,6 +53,7 @@
 
 extern "C" JNIEXPORT jboolean JNICALL Java_Main_sleep(JNIEnv*, jobject, jint, jboolean, jdouble) {
   // Keep pausing.
+  printf("Going to sleep\n");
   for (;;) {
     pause();
   }