RFR(XXS): 8206113: Troubles configuring graal tests

[Ekaterina Pavlova]

Hi All,

please review this extra small change which makes make more silent by
removing info message in case graal unit tests are not built.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8206113
  webrev: http://cr.openjdk.java.net/~epavlova//8206113/webrev.00/index.html

thanks,
-katya

p.s.
  Igor Ignatyev volunteered to sponsor this change.