RFR: JDK-8266431: Dual-Pivot Quicksort improvements (Radix sort) [v8]

[iaroslavski]

> Sorting:
> 
> - adopt radix sort for sequential and parallel sorts on int/long/float/double arrays (almost random and length > 6K)
> - fix tryMergeRuns() to better handle case when the last run is a single element
> - minor javadoc and comment changes
> 
> Testing:
> - add new data inputs in tests for sorting
> - add min/max/infinity values to float/double testing
> - add tests for radix sort

iaroslavski has updated the pull request incrementally with one additional commit since the last revision:

  JDK-8266431: Dual-Pivot Quicksort improvements (Radix sort)
  
  - Set limit for buffer length
  - Radix sort is invoked on fully random data
  - Use 3 steps in Radix sort isntead of 4 for int/float
  - Set better options for parallel sorting

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3938/files
  - new: https://git.openjdk.java.net/jdk/pull/3938/files/ee7f6e82..e1b01cfb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3938&range=07
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3938&range=06-07

  Stats: 182 lines in 2 files changed: 46 ins; 59 del; 77 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3938.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3938/head:pull/3938

PR: https://git.openjdk.java.net/jdk/pull/3938