RFR: 8265326: Strange Characters in G1GC GC Log

[Fairoz Matte]

There was an character formating issue on mac-os due to usage of "
`FormatBuffer<128>`" 
Used explicit variable to hold the FormatBuffer

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Commit messages:
 - 8265326: Strange Characters in G1GC GC Log

Changes: https://git.openjdk.java.net/jdk/pull/3589/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3589&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265326
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3589.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3589/head:pull/3589

PR: https://git.openjdk.java.net/jdk/pull/3589