Alias the av_stream_get_first_dts definition added by Chromium in
their bundled fork.

Taken from Arch Linux:

  https://github.com/archlinux/svntogit-packages/blob/38fd5d2f2e0ade932aa7a80b7dea26215fc41854/trunk/unbundle-ffmpeg-av_stream_get_first_dts.patch

diff --git a/build/linux/unbundle/ffmpeg.gn b/build/linux/unbundle/ffmpeg.gn
--- a/build/linux/unbundle/ffmpeg.gn
+++ b/build/linux/unbundle/ffmpeg.gn
@@ -12,6 +12,7 @@ pkg_config("system_ffmpeg") {
     "libavformat",
     "libavutil",
   ]
+  defines = [ "av_stream_get_first_dts(stream)=stream->first_dts" ]
 }
 
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<tr><td><span title='2024-05-15 15:42:42 +0300'>2024-05-15</span></td><td><a href='/guix/commit/gnu/packages/arcan.scm?id=90d0299cfc435b2aa86df1f03f4ab36136903bb9'>gnu: arcan-sdl: Build with sdl2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/arcan.scm (arcan-sdl)[inputs]: Remove sdl, add sdl2.
[arguments]: Adjust configure-flags to remove a flag specifying sdl
version and add a flag to use the package's default sdl.

Change-Id: I691e37e682aee671752fbdcd9f5a233607fd3f29
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2024-04-11 12:38:23 +0200'>2024-04-11</span></td><td><a href='/guix/commit/gnu/packages/arcan.scm?id=43719864cfdfdea0dcae451af519da629c5ddd86'>gnu: Add durden.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/arcan.scm (durden): New variable.
* gnu/packages/patches/durden-shadow-arcan.patch: New file.
* gnu/local.mk: Register it.

Change-Id: I3ea34563c74c227eed40f4ad50d23713c45ce70b
Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Ahmad Draidi</td></tr>
<tr><td><span title='2024-03-30 10:09:34 +0100'>2024-03-30</span></td><td><a href='/guix/commit/gnu/packages/arcan.scm?id=139715d0e0133700085f8000fb3bbc0482fd53ff'>gnu: xarcan: Update to 0.6.3.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/arcan.scm (xarcan): Update to 0.6.3.

Change-Id: I2480ec0b91e4248b1bc6b6d86f8ed7266a3b95ea
Signed-off-by: Liliana Marie Prikler &lt;liliana.prikler@gmail.com&gt;
</span></span></td><td>Ahmad Draidi</td></tr>
<tr><td><span title='2024-03-30 10:09:33 +0100'>2024-03-30</span></td><td><a href='/guix/commit/gnu/packages/arcan.scm?id=0b88687971157382552c98014430980abb0e5ccd'>gnu: arcan: Update to 0.6.3.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/arcan.scm (arcan): Update to 0.6.3.

Change-Id: I9b1337e578cdc7d290517ace3b0edb6a3fe6e926
Signed-off-by: Liliana Marie Prikler &lt;liliana.prikler@gmail.com&gt;
</span></span></td><td>Ahmad Draidi</td></tr>
<tr><td><span title='2024-03-22 11:40:33 +0100'>2024-03-22</span></td><td><a href='/guix/commit/gnu/packages/arcan.scm?id=c4e25bf1fea5cdb10241b921ac64f7b701641e14'>gnu: arcan-sdl: Add missing inputs.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/arcan.scm (arcan-sdl)[inputs]: Add glu, libglvnd and mesa.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>David Elsing</td></tr>