RFR: 8275162: Replace 'def' macros in mutexLocker.cpp

[Coleen Phillimore]

This patch removes the 'def' macros from mutexLocker.cpp so it can use the default values for _allow_vm_block when possible and no more macro.
Tested with tier1-3 with product and debug builds.

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Commit messages:
 - 8275162: Replace 'def' macros in mutexLocker.cpp

Changes: https://git.openjdk.java.net/jdk/pull/6066/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6066&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275162
  Stats: 117 lines in 2 files changed: 2 ins; 17 del; 98 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6066.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6066/head:pull/6066

PR: https://git.openjdk.java.net/jdk/pull/6066