RFR: 8272725: G1: replace type needs_remset_update_t with bool

[Albert Mingkun Yang]

Simple type change in `struct G1HeapRegionAttr`.

Test: hotspot_gc

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Commit messages:
 - boolean

Changes: https://git.openjdk.java.net/jdk/pull/5188/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5188&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272725
  Stats: 4 lines in 1 file changed: 0 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5188.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5188/head:pull/5188

PR: https://git.openjdk.java.net/jdk/pull/5188