[Buildstream SDK] x265 encoder support

https://bugs.webkit.org/show_bug.cgi?id=259242

Reviewed by Carlos Alberto Lopez Perez.

For WPT WebCodec tests we need an HEVC software encoder, since the bots don't have GPU capabilities
for hardware encoding.

* Tools/buildstream/elements/freedesktop-sdk.bst:
* Tools/buildstream/elements/sdk-platform.bst:
* Tools/buildstream/patches/fdo-0009-gst-plugins-bad-Enable-x265-encoder.patch: Added.

Canonical link: https://commits.webkit.org/266098@main

Tools/buildstream/elements/freedesktop-sdk.bst

@@ -22,6 +22,8 @@ sources:
   path: patches/fdo-0007-components-Bump-GLib-to-version-2.76.patch
 - kind: patch
   path: patches/fdo-0008-components-Bump-g-i-to-version-1.76.patch
+- kind: patch
+  path: patches/fdo-0009-gst-plugins-bad-Enable-x265-encoder.patch
 config:
   options:
     target_arch: '%{arch}'

Tools/buildstream/elements/sdk-platform.bst

@@ -245,3 +245,6 @@ depends:
 - freedesktop-sdk.bst:components/zip.bst
 - freedesktop-sdk.bst:components/zstd.bst
 - freedesktop-sdk.bst:integration/mtab.bst
+- freedesktop-sdk.bst:components/x265.bst
+- freedesktop-sdk.bst:components/x265-10bits.bst
+- freedesktop-sdk.bst:components/x265-12bits.bst