gnu: ungoogled-chromium: Enable v4l2 video decoder on aarch64.

* gnu/packages/chromium.scm (ungoogled-chromium) [arguments]
<#:configure-flags>: Conditionally add use_v4l2_codec and use_av1_hw_decoder
and set them true on aarch64-linux.  Also ensure that use_vaapi is set to
false on this architecture.

Change-Id: Ib7f1c2d492ccb71df253e621b9cd626ec0942bc6
Signed-off-by: Andreas Enge <andreas@enge.fr>

gnu/packages/chromium.scm

@@ -697,6 +697,13 @@
                      '("use_vaapi=true")
                      '())
 
+              #$@(if (string-prefix? "aarch64" (or (%current-target-system)
+                                                   (%current-system)))
+                     '("use_v4l2_codec=true"
+                       "use_vaapi=false"
+                       "use_av1_hw_decoder=true")
+                     '())
+
               ;; Do not artificially restrict formats supported by system ffmpeg.
               "proprietary_codecs=true"
               "ffmpeg_branding=\"Chrome\""