RFR: JDK-8177107: Reduce memory footprint of java.lang.reflect.Constructor/Method

[Joe Darcy]

Refactoring of Method and Constructor to share a single empty array for parameters and exceptions as well as type variables.

Existing core reflection regression tests pass with the change.

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Commit messages:
 - JDK-8177107: Reduce memory footprint of java.lang.reflect.Constructor/Method

Changes: https://git.openjdk.java.net/jdk/pull/7667/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7667&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8177107
  Stats: 15 lines in 3 files changed: 9 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7667.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7667/head:pull/7667

PR: https://git.openjdk.java.net/jdk/pull/7667