[Cleanup] Add missing #include. Remove useless ones. IWYU part 2.

This is a follow-up to
https://webrtc-review.googlesource.com/c/src/+/106280.
This time the whole code base is covered.
Some files may have not been fixed though, whenever the IWYU tool
was breaking the build.

Bug: webrtc:8311
Change-Id: I2c31f552a87e887d33931d46e87b6208b1e483ef
Reviewed-on: https://webrtc-review.googlesource.com/c/111965
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25830}

rtc_base/fakeclock.h

diff --git a/rtc_base/fakeclock.h b/rtc_base/fakeclock.h
index 2da8c61..5a0bbee 100644
--- a/rtc_base/fakeclock.h
+++ b/rtc_base/fakeclock.h
@@ -11,8 +11,11 @@
 #ifndef RTC_BASE_FAKECLOCK_H_
 #define RTC_BASE_FAKECLOCK_H_
 
+#include <stdint.h>
+
 #include "api/units/time_delta.h"
 #include "rtc_base/criticalsection.h"
+#include "rtc_base/thread_annotations.h"
 #include "rtc_base/timeutils.h"
 
 namespace rtc {