RFR: 8268279: gc/shenandoah/compiler/TestLinkToNativeRBP.java fails after LibraryLookup is gone

[Xin Liu]

LibraryLookup::lookup has been refactored in JDK-8268129. Replace it with SymbolLookup.loaderLookup.

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Commit messages:
 - 8268279: gc/shenandoah/compiler/TestLinkToNativeRBP.java fails after LibraryLookup is gone

Changes: https://git.openjdk.java.net/jdk/pull/4370/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4370&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268279
  Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4370.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4370/head:pull/4370

PR: https://git.openjdk.java.net/jdk/pull/4370