RFR: 8329191: JVMCI compiler warning is truncated

[Doug Simon]

$ java -Djdk.graal.CompilerConfiguration=XXcommunity HelloWorld
[0.035s][warning][jit,compilation] JVMCI compiler disabled after 11 of 11 upcalls had errors (Last error: "uncaught exception in call_HotSpotJVMCIRuntime_compileMethod [jdk.graal.compiler.debug.GraalError: Compiler configuration 'XXcommunity' not found. Available configurations are: enterp

The above message is truncated. It should be:

[0.032s][warning][jit,compilation] JVMCI compiler disabled after 11 of 11 upcalls had errors (Last error: "uncaught exception in call_HotSpotJVMCIRuntime_compileMethod [jdk.graal.compiler.debug.GraalError: Compiler configuration 'XXcommunity' not found. Available configurations are: enterprise, community, economy]"). Use -Xlog:jit+compilation for more detail.


This PR fixes this by using `stringStream` instead of `err_msg` when creating these messages.

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Commit messages:
 - mitigate against truncation of JVMCI error messages

Changes: https://git.openjdk.org/jdk/pull/18513/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18513&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329191
  Stats: 10 lines in 2 files changed: 6 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/18513.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18513/head:pull/18513

PR: https://git.openjdk.org/jdk/pull/18513