RFR: JDK-8261297: NMT: Final report should use scale 1 [v2]

[Thomas Stuefe]

> If PrintNMTStatistics is specified, we write a NMT report to stdout before exiting the VM. This is useful for leak analysis.
> 
> However, the report uses the standard "K" scale, which is shouldn't, since this omits small leaks < 1K. Hence it should use scale=1. This would provide us with a precise exit report. Note that for this to work JDK-8261238 has to be fixed too, which is a separate issue.
> 
> This patch:
> - changes the scale of the final report to 1
> - does some minor cleanup work in the MemReporter class hierarchy (const-ifying scale and the output stream, and establishing 0 as "default scale" as to avoid having the default scale hard coded in four places.

Thomas Stuefe has updated the pull request incrementally with two additional commits since the last revision:

 - Missed one
 - Feedback Zhengyu

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2450/files
  - new: https://git.openjdk.java.net/jdk/pull/2450/files/7bbcb0fa..d2479461

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2450&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2450&range=00-01

  Stats: 13 lines in 3 files changed: 2 ins; 2 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2450.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2450/head:pull/2450

PR: https://git.openjdk.java.net/jdk/pull/2450