tests: Don't use stderr for informational messages

These should go to stdout instead. The next patch will clean this up
with cocci, so no change from fprintf(stdout, to printf( here.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/igt.cocci

@@ -1,3 +1,4 @@
+// Replace open-coded augmented igt_assert/skip/require with macro versions
 @@
 expression Ec;
 expression list[n] Ep;