add missing includes for the build with use_libcxx_modules

This is to fix build error when we set use_libcxx_modules=true in
chromium build.

Bug: chromium:40440396
Change-Id: Iad165a78a6920ccb858567d31fbe5e48d8a7b629
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/371620
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Auto-Submit: Takuto Ikuta <tikuta@google.com>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43574}
diff --git a/modules/audio_coding/neteq/tools/input_audio_file.h b/modules/audio_coding/neteq/tools/input_audio_file.h
index f538b29..e885bb39 100644
--- a/modules/audio_coding/neteq/tools/input_audio_file.h
+++ b/modules/audio_coding/neteq/tools/input_audio_file.h
@@ -11,6 +11,7 @@
 #ifndef MODULES_AUDIO_CODING_NETEQ_TOOLS_INPUT_AUDIO_FILE_H_
 #define MODULES_AUDIO_CODING_NETEQ_TOOLS_INPUT_AUDIO_FILE_H_
 
+#include <stdint.h>
 #include <stdio.h>
 
 #include <string>
diff --git a/modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.cc b/modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.cc
index 3d62bce..377317e 100644
--- a/modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.cc
+++ b/modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.cc
@@ -8,13 +8,14 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.h"
-
+#include <stddef.h>
 #include <stdint.h>
 
 #include <initializer_list>
 #include <vector>
 
+#include "modules/rtp_rtcp/source/rtp_packetizer_av1_test_helper.h"
+
 namespace webrtc {
 
 Av1Obu::Av1Obu(uint8_t obu_type) : header_(obu_type | kAv1ObuSizePresentBit) {}