Include <limits.h> for INT_MAX/INT_MIN.

Found by building with gcc.

Change-Id: I029907e8cd82dbc1a49813e418ca826469da6ac1
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/82570
Reviewed-by: Hui Yingst <nigi@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcrt/bytestring_unittest.cpp b/core/fxcrt/bytestring_unittest.cpp
index 4d1cd2c..7b201c1 100644
--- a/core/fxcrt/bytestring_unittest.cpp
+++ b/core/fxcrt/bytestring_unittest.cpp
@@ -4,6 +4,8 @@
 
 #include "core/fxcrt/bytestring.h"
 
+#include <limits.h>
+
 #include <algorithm>
 #include <iterator>
 #include <vector>
diff --git a/core/fxge/dib/cstretchengine.cpp b/core/fxge/dib/cstretchengine.cpp
index 15ab57a..ef534b5 100644
--- a/core/fxge/dib/cstretchengine.cpp
+++ b/core/fxge/dib/cstretchengine.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fxge/dib/cstretchengine.h"
 
+#include <limits.h>
+
 #include <algorithm>
 #include <type_traits>
 #include <utility>
diff --git a/core/fxge/skia/fx_skia_device.cpp b/core/fxge/skia/fx_skia_device.cpp
index 0b092bc..910cb4c 100644
--- a/core/fxge/skia/fx_skia_device.cpp
+++ b/core/fxge/skia/fx_skia_device.cpp
@@ -4,6 +4,8 @@
 
 #include "core/fxge/skia/fx_skia_device.h"
 
+#include <limits.h>
+
 #include <algorithm>
 #include <utility>
 #include <vector>