RFR: 8260255: C1: LoopInvariantCodeMotion constructor can leave some fields uninitialized

[Rickard Bäckman]

Initialize instance variables to default values to avoid uninitialized values for early return.

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Commit messages:
 - 8260255: C1: LoopInvariantCodeMotion constructor can leave some fields uninitialized

Changes: https://git.openjdk.java.net/jdk/pull/3484/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3484&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260255
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3484.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3484/head:pull/3484

PR: https://git.openjdk.java.net/jdk/pull/3484