Do IWYU for <stdarg.h>.

Include it where va_* functions/types are used. Remove it from
fx_system.h.

Change-Id: I41cbe36979c20a470efafa109ed098dcbd2b1076
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/82711
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfapi/render/cpdf_type3cache.cpp b/core/fpdfapi/render/cpdf_type3cache.cpp
index 5fda300..74fd7d8 100644
--- a/core/fpdfapi/render/cpdf_type3cache.cpp
+++ b/core/fpdfapi/render/cpdf_type3cache.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fpdfapi/render/cpdf_type3cache.h"
 
+#include <stdarg.h>
+
 #include <memory>
 #include <utility>
 
diff --git a/core/fxcrt/bytestring.h b/core/fxcrt/bytestring.h
index 38ada07..2a2092d 100644
--- a/core/fxcrt/bytestring.h
+++ b/core/fxcrt/bytestring.h
@@ -7,6 +7,8 @@
 #ifndef CORE_FXCRT_BYTESTRING_H_
 #define CORE_FXCRT_BYTESTRING_H_
 
+#include <stdarg.h>
+
 #include <functional>
 #include <iosfwd>
 #include <iterator>
diff --git a/core/fxcrt/fx_system.h b/core/fxcrt/fx_system.h
index c77bc99..5b5d0b5 100644
--- a/core/fxcrt/fx_system.h
+++ b/core/fxcrt/fx_system.h
@@ -8,7 +8,6 @@
 #define CORE_FXCRT_FX_SYSTEM_H_
 
 #include <math.h>
-#include <stdarg.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
diff --git a/core/fxcrt/widestring.h b/core/fxcrt/widestring.h
index 402d95f..2c40b1f 100644
--- a/core/fxcrt/widestring.h
+++ b/core/fxcrt/widestring.h
@@ -7,6 +7,8 @@
 #ifndef CORE_FXCRT_WIDESTRING_H_
 #define CORE_FXCRT_WIDESTRING_H_
 
+#include <stdarg.h>
+
 #include <functional>
 #include <iosfwd>
 #include <iterator>
diff --git a/core/fxge/cfx_glyphcache.cpp b/core/fxge/cfx_glyphcache.cpp
index c5885b1..253b1ab 100644
--- a/core/fxge/cfx_glyphcache.cpp
+++ b/core/fxge/cfx_glyphcache.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fxge/cfx_glyphcache.h"
 
+#include <stdarg.h>
+
 #include <algorithm>
 #include <limits>
 #include <memory>
diff --git a/fxjs/js_define.cpp b/fxjs/js_define.cpp
index 46acf24..950b287 100644
--- a/fxjs/js_define.cpp
+++ b/fxjs/js_define.cpp
@@ -6,6 +6,8 @@
 
 #include "fxjs/js_define.h"
 
+#include <stdarg.h>
+
 #include <algorithm>
 #include <cmath>
 #include <limits>