[lworld] RFR: 8372394: [lworld] c1_LIRGenerator.cpp(2313): warning C4267: 'argument': conversion from 'size_t' to 'int'

[Paul Hübner]

Hi all,

This fixes build failures on Windows due to a missed `size_t` to `int` narrowing in an argument. This was a result of increasing the size of an offset to a `size_t` in [https://bugs.openjdk.org/browse/JDK-8371604](https://bugs.openjdk.org/browse/JDK-8371604). 

I've taken a look at the original PR and noticed that a test file doesn't reference the specially-created constant. I've gone ahead and fixed that too.

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Commit messages:
 - Add proper constant reference to test.
 - C1: Fix size_t narrowing to int.

Changes: https://git.openjdk.org/valhalla/pull/1758/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1758&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8372394
  Stats: 4 lines in 3 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/valhalla/pull/1758.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1758/head:pull/1758

PR: https://git.openjdk.org/valhalla/pull/1758