RFR(T): 8223137: Rename predicate 'do_unroll_only()' to 'is_unroll_only()'.

[Patric Hedlin]

Dear all,

I would like to ask for help to review the following change/update:

Issue:  https://bugs.openjdk.java.net/browse/JDK-8223137
Webrev: http://cr.openjdk.java.net/~phedlin/tr8223137/

8223137: Rename predicate 'do_unroll_only()' to 'is_unroll_only()'.

     The "do" prefix is used as a command ditto elsewhere, while 
predicates typically use "is".


Testing: Part of 8216137 (hs-tier1..4, hs-precheckin-comp, Kitchensink24h)


Best regards,
Patric