[jdk20u] RFR: 8300079: SIGSEGV in LibraryCallKit::inline_string_copy due to constant NULL src argument

[Tobias Hartmann]

Backport of [JDK-8300079](https://bugs.openjdk.java.net/browse/JDK-8300079). Applies cleanly. Approval is pending.

Thanks,
Tobias

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Commit messages:
 - 8300079: SIGSEGV in LibraryCallKit::inline_string_copy due to constant NULL src argument

Changes: https://git.openjdk.org/jdk20u/pull/32/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk20u&pr=32&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300079
  Stats: 186 lines in 2 files changed: 62 ins; 32 del; 92 mod
  Patch: https://git.openjdk.org/jdk20u/pull/32.diff
  Fetch: git fetch https://git.openjdk.org/jdk20u.git pull/32/head:pull/32

PR: https://git.openjdk.org/jdk20u/pull/32