RFR: 8293170: Improve encoding of the debuginfo nmethod section [v13]

[Boris Ulasevich]

> The nmethod "scopes data" section is 10% of the size of nmethod. Now the data is compressed using the Pack200 algorithm, which is good for encoding small integers (LineNumberTable, etc). Using the fact that half of the data in the partition contains zeros, I reduce its size by another 30%.
>  
> Testing: jtreg hotspot&jdk, Renaissance benchmarks

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

  minor api refactoring: start_scope and roll_back instead of position and set_position

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10025/files
  - new: https://git.openjdk.org/jdk/pull/10025/files/a24683d9..477609da

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10025&range=12
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10025&range=11-12

  Stats: 95 lines in 3 files changed: 19 ins; 1 del; 75 mod
  Patch: https://git.openjdk.org/jdk/pull/10025.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10025/head:pull/10025

PR: https://git.openjdk.org/jdk/pull/10025