Remove PRIuS define from fx_system.h.

Nobody actually uses it. If PDFium uses it in the future, borrow
Chromium's base/format_macros.h instead.

Change-Id: Ic98ea0fb364c69d20728bebcf36405b1a277cbdf
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/70890
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/core/fxcrt/fx_system.h b/core/fxcrt/fx_system.h
index b7c3ffa..135116c 100644
--- a/core/fxcrt/fx_system.h
+++ b/core/fxcrt/fx_system.h
@@ -188,33 +188,4 @@
 }  // extern C
 #endif  // __cplusplus
 
-// To print a size_t value in a portable way:
-//   size_t size;
-//   printf("xyz: %" PRIuS, size);
-// The "u" in the macro corresponds to %u, and S is for "size".
-#if !defined(OS_WIN)
-
-#if (defined(_INTTYPES_H) || defined(_INTTYPES_H_)) && !defined(PRId64)
-#error "inttypes.h has already been included before this header file, but "
-#error "without __STDC_FORMAT_MACROS defined."
-#endif
-
-#if !defined(__STDC_FORMAT_MACROS)
-#define __STDC_FORMAT_MACROS
-#endif
-
-#include <inttypes.h>
-
-#if !defined(PRIuS)
-#define PRIuS "zu"
-#endif
-
-#else  // !defined(OS_WIN)
-
-#if !defined(PRIuS)
-#define PRIuS "Iu"
-#endif
-
-#endif  // !defined(OS_WIN)
-
 #endif  // CORE_FXCRT_FX_SYSTEM_H_