Remove built-in sw codecs from decoder_database.

All decoders are injectable, no need to create built-in codecs from
there.

Bug: webrtc:7925
Change-Id: Iabf3d59a8e4d721ad29386acbf138b7e5992ce5e
Reviewed-on: https://webrtc-review.googlesource.com/72441
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23397}
diff --git a/video/BUILD.gn b/video/BUILD.gn
index 2ef8473..d18f334 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -112,7 +112,7 @@
 
 rtc_source_set("video_stream_decoder_impl") {
   visibility = [ "*" ]
-  allow_poison = [ "software_video_codecs" ]  # TODO(bugs.webrtc.org/7925): Remove.
+
   sources = [
     "video_stream_decoder_impl.cc",
     "video_stream_decoder_impl.h",