RFR: 8281335: Allow a library already loaded via System::loadLibrary to be loaded as a raw library [v4]

[Mandy Chung]

> This patch removes the restriction in the raw library loading mechanism that does not allow mix-n-match of loading a library as a JNI library and as a raw library.
> 
> The raw library loading mechanism is designed for panama to load native library essentially equivalent to dlopen/dlclose calls independent of JNI library loading. If a native library is loaded as a JNI library and a raw library, it will get different NativeLibrary instances. When a class loader is being unloaded, JNI_Unload will be invoked but the native library may not be unloaded until NativeLibrary::unload is explicitly called for the raw library.

Mandy Chung has updated the pull request incrementally with one additional commit since the last revision:

  No need for explicit locking for raw loading

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7435/files
  - new: https://git.openjdk.java.net/jdk/pull/7435/files/755c67d9..1be1afad

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7435&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7435&range=02-03

  Stats: 45 lines in 2 files changed: 14 ins; 18 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7435.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7435/head:pull/7435

PR: https://git.openjdk.java.net/jdk/pull/7435