RFR (M): 8235860: Obsolete the UseParallelOldGC option

[Thomas Schatzl]

Hi all,

   can I get reviews for this change that implements obsoletion of the 
UseParallelOldGC option, i.e. removal of the Parallel GC Serial Old 
collector?

((I am counting this as "M" because it's 99% removal of code)

CR:
https://bugs.openjdk.java.net/browse/JDK-8235860
Webrev:
http://cr.openjdk.java.net/~tschatzl/8235860/webrev/
Testing:
hs-tier1-5 almost done

Thanks,
   Thomas