[libc][fix] Use off_t libc type directly

Summary:
Including stdio here caused some multiple definitions on overlay mode.
Just include `off_t` directly.

Is this correct for 32-bit targets? Will investigate further after
fixing bots.

libc/src/__support/File/file.h

@@ -9,14 +9,14 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_FILE_FILE_H
 #define LLVM_LIBC_SRC___SUPPORT_FILE_FILE_H
 
+#include "include/llvm-libc-types/off_t.h"
 #include "src/__support/CPP/new.h"
 #include "src/__support/error_or.h"
 #include "src/__support/macros/properties/architectures.h"
 #include "src/__support/threads/mutex.h"
 
 #include <stddef.h>
 #include <stdint.h>
-#include <stdio.h>
 
 namespace LIBC_NAMESPACE {