RFR: 8311110: multichar warning in WinAccessBridge.cpp

[Abhishek Kumar]

Looks like there was a typo for null character. It should be `'\0'` instead of `'/0'`.
Build with clang toolchain with the help of [this PR](https://github.com/openjdk/jdk/pull/17019) and after the changes there is no warning.

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Commit messages:
 - typo for null character fixed

Changes: https://git.openjdk.org/jdk/pull/19670/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19670&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311110
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19670.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19670/head:pull/19670

PR: https://git.openjdk.org/jdk/pull/19670