RFR: 8273218: G1: Rename g1EvacuationInfo to g1EvacInfo

[Hamlin Li]

This is a minor cleanup to rename g1EvacuationInfo to g1EvacInfo, as other similar files are named as EvacXxx.

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Commit messages:
 - Rename g1EvacuationInfo.hpp to g1EvacInfo.hpp, and related class names

Changes: https://git.openjdk.java.net/jdk/pull/5325/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5325&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273218
  Stats: 38 lines in 9 files changed: 0 ins; 0 del; 38 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5325.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5325/head:pull/5325

PR: https://git.openjdk.java.net/jdk/pull/5325