RFR: 8344445: MethodCounters don't need a vptr [v2]

[Coleen Phillimore]

> This is a somewhat trivial change to make MethodCounters inherit from MetaspaceObj so that they don't have any virtual functions (and vptrs).  They're just a bunch of ints.
> 
> Tested with tier1-4.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Remove method_pointers_size() in favor of static size().

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22220/files
  - new: https://git.openjdk.org/jdk/pull/22220/files/fafb86ff..f0a55222

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22220&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22220&range=00-01

  Stats: 6 lines in 2 files changed: 0 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22220.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22220/head:pull/22220

PR: https://git.openjdk.org/jdk/pull/22220