RFR: 8277439: G1: Correct include guard name in G1EvacFailureObjectsSet.hpp

[Hamlin Li]

This is a trivial patch to fix the include guard name in G1EvacFailureObjectsSet.hpp

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.java.net/jdk/pull/6474/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6474&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277439
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6474.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6474/head:pull/6474

PR: https://git.openjdk.java.net/jdk/pull/6474