RFR: JDK-8282382: Report glibc malloc tunables in error reports [v2]

[Thomas Stuefe]

> On Linux/glibc platforms, the hs-err file should report the malloc tunables, or at least MALLOC_ARENA_MAX, since that one can have a significant effect on footprint or malloc contention for a VM.
> 
> This patch adds this printout as a one-liner into hs-err files and jcmd VM.info reports:
> 
> 
> Process Memory:                                                                    
> ...
> glibc malloc tunables: MALLOC_PERTURB_=40, MALLOC_ARENA_MAX=1
> 
> 
> If the tunables are default, we print `glibc malloc tunables: (default)`.
> 
> 
> Thanks, Thomas

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

  Zhengyus feedback, comment fixes, added SAP copyright

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7620/files
  - new: https://git.openjdk.java.net/jdk/pull/7620/files/83d38ff0..a462e6e8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7620&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7620&range=00-01

  Stats: 11 lines in 1 file changed: 3 ins; 2 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7620.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7620/head:pull/7620

PR: https://git.openjdk.java.net/jdk/pull/7620