[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/rtc_base/timeutils.h b/rtc_base/timeutils.h
index 3a412a4..4e38a03 100644
--- a/rtc_base/timeutils.h
+++ b/rtc_base/timeutils.h
@@ -13,8 +13,6 @@
 
 #include <stdint.h>
 #include <time.h>
-
-#include <ctime>
 #include <string>
 
 #include "rtc_base/checks.h"
@@ -110,10 +108,10 @@
   int64_t num_wrap_;
 };
 
-// Convert from std::tm, which is relative to 1900-01-01 00:00 to number of
-// seconds from 1970-01-01 00:00 ("epoch").  Don't return time_t since that
+// Convert from tm, which is relative to 1900-01-01 00:00 to number of
+// seconds from 1970-01-01 00:00 ("epoch"). Don't return time_t since that
 // is still 32 bits on many systems.
-int64_t TmToSeconds(const std::tm& tm);
+int64_t TmToSeconds(const tm& tm);
 
 // Return the number of microseconds since January 1, 1970, UTC.
 // Useful mainly when producing logs to be correlated with other