RFR: JDK-8299972: Remove metaprogramming/removeReference.hpp

[Justin King]

Code cleanup of pre-C++11 <type_traits> implementations.

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Commit messages:
 - Remove metaprogramming/removeReference.hpp

Changes: https://git.openjdk.org/jdk/pull/11947/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299972
  Stats: 83 lines in 2 files changed: 0 ins; 83 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11947.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11947/head:pull/11947

PR: https://git.openjdk.org/jdk/pull/11947