RFR (S): 8210265: Crash in HSpaceCounters::update_used()

[Thomas Schatzl]

Hi all,

  can I have reviews for this change that fixes a crash when G1 is
started with -XX:-UsePerfData?
The reason has been that recent refactoring removed one "if
(UsePerfData)" check too many.

CR:
https://bugs.openjdk.java.net/browse/JDK-8210265
Webrev:
http://cr.openjdk.java.net/~tschatzl/8210265/webrev/
Testing:
new test succeeds

Thanks,
  Thomas