RFR (XXS): 8252231: G1AdaptiveIHOP has swapped current_occupancy and additional_buffer_size

[Thomas Schatzl]

Hi all,

   can I have reviews for this change Aleksey found recently (for which 
my thanks!): when sending adaptive IHOP statistics JFR event, the 
"current occupancy" and "additional buffer size" fields were swapped 
along the way.

CR:
https://bugs.openjdk.java.net/browse/JDK-8252231
Webrev:
http://cr.openjdk.java.net/~tschatzl/8252231/webrev/
Testing:
local compilation

Thanks,
   Thomas