RFR: 8263992: Remove dead code NativeLookup::base_library_lookup

[Ioi Lam]

Please review this trivial removal of dead code. The word `base_library_lookup` does not exist in any C source code in the entire JDK.

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Commit messages:
 - 8263992: Remove dead code NativeLookup::base_library_lookup

Changes: https://git.openjdk.java.net/jdk/pull/3139/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3139&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263992
  Stats: 24 lines in 2 files changed: 0 ins; 23 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3139.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3139/head:pull/3139

PR: https://git.openjdk.java.net/jdk/pull/3139