[jfx15] RFR: 8250238: Media fails to load libav 58 library when using modules from maven central

[Kevin Rushforth]

When running a JavaFX application using the JavaFX modules from maven central, the native libraries are packed into the
jar file, and then unpacked as needed by the JavaFX runtime. This fails for libavplugin-ffmpeg-58.so, because the entry
for the `avplugin-ffmpeg-58` library is missing from the list of dependent libraries of `jfxmedia` in
[NativeMediaManager.java](https://github.com/openjdk/jfx/blob/14-ga/modules/javafx.media/src/main/java/com/sun/media/jfxmediaimpl/NativeMediaManager.java#L118).

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Commit messages:
 - 8250238: Media fails to load libav 58 library when using modules from maven central

Changes: https://git.openjdk.java.net/jfx/pull/272/files
 Webrev: https://webrevs.openjdk.java.net/jfx/272/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8250238
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/272.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/272/head:pull/272

PR: https://git.openjdk.java.net/jfx/pull/272