Mark built-in software video codecs as poisonous.

The goal is to make these injectable, and only VP8 and VP9 specific
targets should depend on them.

Bug: webrtc:7925
Change-Id: Ie9239a54d197fe70c93de0582797211fef6997a2
Reviewed-on: https://webrtc-review.googlesource.com/72082
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23021}
diff --git a/modules/video_coding/BUILD.gn b/modules/video_coding/BUILD.gn
index 555a3b4..a880109 100644
--- a/modules/video_coding/BUILD.gn
+++ b/modules/video_coding/BUILD.gn
@@ -38,7 +38,10 @@
 
 rtc_static_library("video_coding") {
   visibility = [ "*" ]
-  allow_poison = [ "audio_codecs" ]  # TODO(bugs.webrtc.org/8396): Remove.
+  allow_poison = [
+    "audio_codecs",  # TODO(bugs.webrtc.org/8396): Remove.
+    "software_video_codecs",  # TODO(bugs.webrtc.org/7925): Remove.
+  ]
   deps = []
 
   sources = [
@@ -406,6 +409,7 @@
 # This target includes the internal SW codec.
 rtc_static_library("webrtc_vp8") {
   visibility = [ "*" ]
+  poisonous = [ "software_video_codecs" ]
   sources = [
     "codecs/vp8/include/vp8.h",
     "codecs/vp8/include/vp8_common_types.h",
@@ -474,6 +478,7 @@
 
 rtc_static_library("webrtc_vp9") {
   visibility = [ "*" ]
+  poisonous = [ "software_video_codecs" ]
   if (rtc_libvpx_build_vp9) {
     sources = [
       "codecs/vp9/include/vp9.h",