RFR: 8255562: delete UseRDPCForConstantTableBase [v2]

[Xin Liu]

> UseRDPCForConstantTableBase was a SPARC-exclusive flag. Sparc has been removed 
> from hotspot, so remove this flag.

Xin Liu has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains two new commits since the last revision:

 - 8255562: delete UseRDPCForConstantTableBase
   
   mark UseRDPCForConstantTableBase is obsoletd in jdk16 and will expire in jdk17.
 - 8255562: delete UseRDPCForConstantTableBase

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/949/files
  - new: https://git.openjdk.java.net/jdk/pull/949/files/a4e875e8..478aab95

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=949&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=949&range=00-01

  Stats: 13 lines in 3 files changed: 8 ins; 3 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/949.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/949/head:pull/949

PR: https://git.openjdk.java.net/jdk/pull/949