IWYU: add cstdint for uint8_t in fxcrt::UnownedPtr

Bug: chromium:957519
Change-Id: I23458e33527e14abc824918bfdce704f1f7363e5
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/106990
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

core/fxcrt/unowned_ptr.h

diff --git a/core/fxcrt/unowned_ptr.h b/core/fxcrt/unowned_ptr.h
index 1a2c9bb..236f6e8 100644
--- a/core/fxcrt/unowned_ptr.h
+++ b/core/fxcrt/unowned_ptr.h
@@ -12,6 +12,10 @@
 
 #include "third_party/base/compiler_specific.h"
 
+#if defined(ADDRESS_SANITIZER)
+#include <cstdint>
+#endif
+
 // UnownedPtr is a smart pointer class that behaves very much like a
 // standard C-style pointer. The advantages of using it over raw
 // pointers are: