[jfx11u] RFR: 8269147: Update GStreamer to version 1.18.4

[Kevin Rushforth]

Clean backport of third-party update to GStreamer 1.18.4.

As an FYI, I tested this patch in my [test-kcr-11.0.13](https://github.com/kevinrushforth/jfx11u/tree/test-kcr-11.0.13) branch, which has the aggregate set of patches for the following bugs: [JDK-8211308](https://bugs.openjdk.java.net/browse/JDK-8211308), [JDK-8268915](https://bugs.openjdk.java.net/browse/JDK-8268915), [JDK-8269147](https://bugs.openjdk.java.net/browse/JDK-8269147), [JDK-8269131](https://bugs.openjdk.java.net/browse/JDK-8269131), [JDK-8268849](https://bugs.openjdk.java.net/browse/JDK-8268849), [JDK-8270479](https://bugs.openjdk.java.net/browse/JDK-8270479), [JDK-8272329](https://bugs.openjdk.java.net/browse/JDK-8272329).

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Commit messages:
 - 8269147: Update GStreamer to version 1.18.4

Changes: https://git.openjdk.java.net/jfx11u/pull/32/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=32&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8269147
  Stats: 178 lines in 18 files changed: 82 ins; 3 del; 93 mod
  Patch: https://git.openjdk.java.net/jfx11u/pull/32.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/32/head:pull/32

PR: https://git.openjdk.java.net/jfx11u/pull/32