RFR: 8298913: Add override qualifiers to Relocation classes [v2]

[Kim Barrett]

> Please review this change to the Relocation classes, adding `override`
> qualifiers to all overriding virtual function declarations.
> 
> Testing:
> mach5 tier1
> 
> Note that building with clang (on macosx) subjected these changes to clang's
> `-Winconsistent-missing-override` option.
> 
> Note that there are a lot of member functions missing `const` qualifiers in
> the Relocation hierarchy.  I may look at improving const-correctness later.
> After doing a little exploration down that path, it looks like it might be a
> bit messy.

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into reloc-override
 - add override qualifiers

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11716/files
  - new: https://git.openjdk.org/jdk/pull/11716/files/236514d5..26897139

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11716&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11716&range=00-01

  Stats: 3667 lines in 194 files changed: 2118 ins; 618 del; 931 mod
  Patch: https://git.openjdk.org/jdk/pull/11716.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11716/head:pull/11716

PR: https://git.openjdk.org/jdk/pull/11716