[jdk11u-dev] RFR: 8252051: Make mlvmJvmtiUtils strncpy uses GCC 10.x friendly

[Joshua Cao]

Backport of 51a3b25d71e0. Removing Pragma's that ignore the stringop-truncation warning, which does not exist in tip. This backport eliminates the need for the warnings. The change is in test code so no danger of regressions in hotspot.

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Commit messages:
 - Backport 51a3b25d71e0

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/475/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=475&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252051
  Stats: 13 lines in 1 file changed: 2 ins; 9 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/475.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/475/head:pull/475

PR: https://git.openjdk.java.net/jdk11u-dev/pull/475