Debugging a POST failure when it prints nothing is painful. The
|check_test| helper already prints out information when it fails, but
some other paths were not handled. This change adds printfs for those
cases.

Change-Id: Ife71bb292a4f69679d0fa56686863aae9423e451
Updating-Note: updates internal bug 116469121
Reviewed-on: https://boringssl-review.googlesource.com/32145
Reviewed-by: David Benjamin <davidben@google.com>