RFR: 8255495: Support CDS Archived Heap for uncompressed oops [v2]

[Calvin Cheung]

> This proposed change adds support for uncompressed oops for CDS archived heap. It is needed
> for supporting archived heap for ZGC in the future. For now, only G1GC is supported with this change.
> During dump time with compressed oops disabled, the MaxHeapSize is set to 4GB. This is to ensure
> the offset of any object in the heap from the bottom of the heap is always a 32-bit integer.
> 
> Passed CI tiers 1 - 4 and hs-tier7-rt tests.
> 
> Preliminary HelloWorld startup perf. improvement:
> 
> instr delta =    -68813432    -49.7140%
> time  delta =      -14.720 ms -20.3599%

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

  @iklam comments

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7223/files
  - new: https://git.openjdk.java.net/jdk/pull/7223/files/885a949e..5ac98ba1

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7223&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7223&range=00-01

  Stats: 88 lines in 8 files changed: 56 ins; 20 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7223.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7223/head:pull/7223

PR: https://git.openjdk.java.net/jdk/pull/7223