[Cleanup] Add missing #include. Remove useless ones.

This CL is the result of running include-what-you-use tool on part
of the code base (audio target and dependencies) plus manual fixes.

bug: webrtc:8311
Change-Id: I277d281ce943c3ecc1bd45fd8d83055931743604
Reviewed-on: https://webrtc-review.googlesource.com/c/106280
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25311}
diff --git a/modules/audio_coding/neteq/sync_buffer.h b/modules/audio_coding/neteq/sync_buffer.h
index 72e320c..d645e91 100644
--- a/modules/audio_coding/neteq/sync_buffer.h
+++ b/modules/audio_coding/neteq/sync_buffer.h
@@ -11,8 +11,13 @@
 #ifndef MODULES_AUDIO_CODING_NETEQ_SYNC_BUFFER_H_
 #define MODULES_AUDIO_CODING_NETEQ_SYNC_BUFFER_H_
 
+#include <stddef.h>
+#include <stdint.h>
+#include <vector>
+
 #include "api/audio/audio_frame.h"
 #include "modules/audio_coding/neteq/audio_multi_vector.h"
+#include "modules/audio_coding/neteq/audio_vector.h"
 #include "rtc_base/buffer.h"
 #include "rtc_base/constructormagic.h"