[cleanup] Remove useless includes.

Manual cleanup guided by include-what-you-use diagnostic.

Bug: webrtc:8311
Change-Id: I00be03392cc7ee005101427ea7dc701621ccea68
Reviewed-on: https://webrtc-review.googlesource.com/c/103320
Commit-Queue: Yves Gerey <yvesg@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25013}
diff --git a/rtc_base/strings/string_builder.h b/rtc_base/strings/string_builder.h
index 186c2f7..27001d1 100644
--- a/rtc_base/strings/string_builder.h
+++ b/rtc_base/strings/string_builder.h
@@ -12,13 +12,11 @@
 #define RTC_BASE_STRINGS_STRING_BUILDER_H_
 
 #include <cstdio>
-#include <cstring>
 #include <string>
+#include <utility>
 
 #include "absl/strings/string_view.h"
 #include "api/array_view.h"
-#include "rtc_base/checks.h"
-#include "rtc_base/numerics/safe_minmax.h"
 #include "rtc_base/stringencode.h"
 #include "rtc_base/stringutils.h"