RFR: 8269147: Update GStreamer to version 1.18.4

Thu Jun 24 13:17:28 UTC 2021

On Thu, 24 Jun 2021 02:50:08 GMT, Alexander Matveev <almatvee at openjdk.org> wrote:

> - GStreamer updated to 1.18.4.
>  - Tested on all platforms with all formats.

The code changes look good. I tested it on all three platforms. No problems.

@tiainen can be the second reviewer on this.

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Marked as reviewed by kcr (Lead).

PR: https://git.openjdk.java.net/jfx/pull/541