Clean up visibility and dependencies of RTC event log build targets.

- Remove visibility of encoder target.
- Remove unnecessary dependency on task_queue.
- Remove CreateRtcEventLogFactory() declaration from the rtc_event_log_api target
  since the function is not defined in that target.

Bug: None
Change-Id: Id9edee86f358d08ea063d62bd96e9653c5b06d55
Reviewed-on: https://webrtc-review.googlesource.com/c/116060
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26215}
diff --git a/examples/objcnativeapi/objc/objccallclient.mm b/examples/objcnativeapi/objc/objccallclient.mm
index c7b2af4..54015b2 100644
--- a/examples/objcnativeapi/objc/objccallclient.mm
+++ b/examples/objcnativeapi/objc/objccallclient.mm
@@ -22,6 +22,7 @@
 #include "api/audio_codecs/builtin_audio_encoder_factory.h"
 #include "api/peerconnectioninterface.h"
 #include "api/video/builtin_video_bitrate_allocator_factory.h"
+#include "logging/rtc_event_log/rtc_event_log_factory.h"
 #include "media/engine/webrtcmediaengine.h"
 #include "modules/audio_processing/include/audio_processing.h"
 #include "sdk/objc/native/api/video_capturer.h"