RFR (XS): 8052170: G1 asserts at collection exit with -XX:-G1DeferredRSUpdate

[Thomas Schatzl]

Hi all,

  can I have reviews for this small change? It fixes an assertion that
triggers when -XX:-G1DeferredRSUpdate and -XX:+PrintGCDetails is set. In
particular in this case the timing measurements introduced in
JDK-8019342 are not updated during GC, causing this issue.

The existing test case introduced in 8040977 does not trigger either,
because it does not enable PrintGCDetails.

The fix is to initialize these timing metrics also in case
G1DeferredRSUpdate is disabled.

I also moved the checking whether G1DeferredRSUpdate is enabled into
G1CollectedHeap::redirty_logged_cards() as similar code style has been
suggested for the eager reclaim change.

I updated the existing test case too.

CR:
https://bugs.openjdk.java.net/browse/JDK-8052170

Webrev:
http://cr.openjdk.java.net/~tschatzl/8052170/webrev

Testing:
jprt, jtreg test case

Thanks,
  Thomas