Add missing dependency to audio_decoder_unittests.

BUG=None
NOTRY=True
R=kjellander@webrtc.org

Review-Url: https://codereview.webrtc.org/2684573002
Cr-Original-Commit-Position: refs/heads/master@{#16470}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 87b8e9f3a24dfc08f3e3f9bf5cf8f01c2ae04a4c
diff --git a/modules/audio_coding/BUILD.gn b/modules/audio_coding/BUILD.gn
index 00b9aa2..05dfbc3 100644
--- a/modules/audio_coding/BUILD.gn
+++ b/modules/audio_coding/BUILD.gn
@@ -1325,6 +1325,7 @@
     deps += audio_coding_deps
     deps += [
       ":audio_decoder_interface",
+      ":ilbc",
       ":isac",
       ":isac_fix",
       ":neteq",