RFR: 8265682: G1: Mutex::_name dangling in HeapRegionRemSet references after JDK-8264146 [v2]

[Coleen Phillimore]

> This change makes the Mutex constructor stdup the name passed in for the few cases that the name is constructed on the stack.  Most names are shorter than 64 characters so it's still a savings.
> Tested with tier1.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  use ASSERT_STREQ

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3639/files
  - new: https://git.openjdk.java.net/jdk/pull/3639/files/fec5c8af..9baa7ae5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3639&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3639&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3639.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3639/head:pull/3639

PR: https://git.openjdk.java.net/jdk/pull/3639