RFR: 8257709: C1: Double assignment in InstructionPrinter::print_stack

[Sergey Platonov]

There is currently a minor bug (just a typo, actually) in the hotspot, leading
to undefined behavior.

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Commit messages:
 - 8257709: C1: Double assignment in InstructionPrinter::print_stack

Changes: https://git.openjdk.java.net/jdk/pull/1519/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1519&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8257709
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1519.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1519/head:pull/1519

PR: https://git.openjdk.java.net/jdk/pull/1519