RFR: 8266822: Rename MetaspaceShared::is_old_class to has_old_class_version [v5]

[Calvin Cheung]

> Please review this simple patch for renaming the function from `MetaspaceShared::is_old_class` to `MetaspaceShared::has_old_class_version`. Also added some comment to the function.
> 
> Tests:
> - [x] tier1, 2

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

  convert has_old_class_version to an instance method

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3983/files
  - new: https://git.openjdk.java.net/jdk/pull/3983/files/cb45e49b..ce372118

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3983&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3983&range=03-04

  Stats: 18 lines in 6 files changed: 0 ins; 3 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3983.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3983/head:pull/3983

PR: https://git.openjdk.java.net/jdk/pull/3983