RFR: 8325259: Serial: Inline OldGenScanClosure during Young GC [v4]

[Albert Mingkun Yang]

> Simple inlining oop closure during card-scanning of young-gc.
> 
> Test: using the attached card-scanning-stressing benchmark, ~5x improvement (in terms of young-gc pause time) is observed on my box.

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  Update src/hotspot/share/gc/serial/defNewGeneration.cpp
  
  Co-authored-by: Thomas Schatzl <59967451+tschatzl at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17711/files
  - new: https://git.openjdk.org/jdk/pull/17711/files/ac74cdef..3015a94b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17711&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17711&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17711.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17711/head:pull/17711

PR: https://git.openjdk.org/jdk/pull/17711