RFR (XXS): 8155811: Remove HeapRegionRemSet::_coarse_dirty flag

[Thomas Schatzl]

Hi all,

  can I have reviews for this change that contains a suggestion by Jon
about improving the JDK-8155233 change?

I forgot to merge it in the JDK-8155233 change before pushing.

Since this change actually has already been reviewed, I would like to
consider it a trivial change, waiving the 24 hour review rule (if
possible).

CR:
https://bugs.openjdk.java.net/browse/JDK-8155811
Webrev:
http://cr.openjdk.java.net/~tschatzl/8155811/webrev/
Testing:
jprt

Thanks,
  Thomas