RFR: 8337031: Improvements to CompilationMemoryStatistic [v2]

[Ashutosh Mehra]

> Some minor improvements to CompilationMemoryStatistic. More details are in [JDK-8337031](https://bugs.openjdk.org/browse/JDK-8337031)
> 
> Testing:
>   test/hotspot/jtreg/compiler/print/CompileCommandPrintMemStat.java
>   test/hotspot/jtreg/serviceability/dcmd/compiler/CompilerMemoryStatisticTest.java

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

  Address review comments by Thomas S.
  
  Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20304/files
  - new: https://git.openjdk.org/jdk/pull/20304/files/1ffbd696..008ac6b9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20304&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20304&range=00-01

  Stats: 91 lines in 4 files changed: 31 ins; 30 del; 30 mod
  Patch: https://git.openjdk.org/jdk/pull/20304.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20304/head:pull/20304

PR: https://git.openjdk.org/jdk/pull/20304