RFR: 8294907: Remove unused NativeLookup::dll_load

[Albert Mingkun Yang]

Trivial change of removing dead code.

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Commit messages:
 - nativelookup-remove

Changes: https://git.openjdk.org/jdk/pull/10595/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10595&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294907
  Stats: 19 lines in 2 files changed: 0 ins; 19 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10595.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10595/head:pull/10595

PR: https://git.openjdk.org/jdk/pull/10595