RFR: 8292891: ifdef-out some CDS-only functions [v3]

[Ioi Lam]

> Some CDS functions are always compiled, even when CDS is not enabled (e.g., for the minimal VM).
> 
> This RFE puts some of the obvious ones inside `#if INCLUDE_CDS` blocks. 
> 
> Note: my goal is not to make the minimal VM as small as possible. But rather, I don't want to put `#if INCLUDE_CDS` inside each of those functions that access a CDS-only feature. (E.g., `ConstantPoolCache::save_for_archive`, which accesses `_initial_entries`, which is declared only when CDS is enabled).

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  @dholmes-ora and @coleenp comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10010/files
  - new: https://git.openjdk.org/jdk/pull/10010/files/9941eb7e..17a20bde

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10010&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10010&range=01-02

  Stats: 5 lines in 2 files changed: 2 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/10010.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10010/head:pull/10010

PR: https://git.openjdk.org/jdk/pull/10010