RFR(T/XS) 8215728: [Graal] we should run some Graal tests in tier1

[Ekaterina Pavlova]

Hi,

please review this small patch which defines jtreg test group 'tier1_compiler_graal' so we can run it
as part of tier1 testing. compiler/graalunit/HotspotTest.java is the most frequent failed test based on
bugs statistics, so I included only this group of tests for now. They also takes reasonable amount of
time to execute.

      JBS: https://bugs.openjdk.java.net/browse/JDK-8215728
   webrev: http://cr.openjdk.java.net/~epavlova//8215728/webrev.00/index.html
  testing: tier1


thanks,
-katya