RFR: JDK-8300260: Remove metaprogramming/isSame.hpp [v3]

[Justin King]

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

Justin King has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Merge branch 'master' into remove-is-same
 - Revert back from std::is_void to std::is_same
   
   Signed-off-by: Justin King <jcking at google.com>
 - Remove metaprogramming/isSame.hpp
   
   Signed-off-by: Justin King <jcking at google.com>

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Changes: https://git.openjdk.org/jdk/pull/12040/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12040&range=02
  Stats: 111 lines in 7 files changed: 2 ins; 93 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/12040.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12040/head:pull/12040

PR: https://git.openjdk.org/jdk/pull/12040