[msan] Use REAL macro when calling intercepted function

[eugenis]

This code needs to call the interceptor to unpoison the output buffer.

As an alternative, unpoison the buffer after the REAL call (just copy the chunk from the previous function).

What problem does this change solve?

[tstellar]

In D92518#2432531, @eugenis wrote:

This code needs to call the interceptor to unpoison the output buffer.

As an alternative, unpoison the buffer after the REAL call (just copy the chunk from the previous function).

What problem does this change solve?

It fixes a compile error introduced in D92521 where I attempt to change the name of the interceptor. I thought based on the comments that the REAL() macro was necessary, but sound like I was wrong. Maybe it would be best to look at D92521 first, because that is the main problem I'm trying to fix.

[vitalybuka]

I guess it's not needed as D92521 after D93877

compiler-rt/lib/msan/msan_interceptors.cpp

 //===-- msan_interceptors.cpp ---------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
INTERCEPTOR(int, vswprintf, void *str, uptr size, void *format, va_list ap) {
   }
   return res;
 }
 
 INTERCEPTOR(int, swprintf, void *str, uptr size, void *format, ...) {
   ENSURE_MSAN_INITED();
   va_list ap;
   va_start(ap, format);
-  int res = vswprintf(str, size, format, ap);
+  int res = REAL(vswprintf)(str, size, format, ap);
   va_end(ap);
   return res;
 }
 
 #define INTERCEPTOR_STRFTIME_BODY(char_type, ret_type, func, s, ...) \
   ENSURE_MSAN_INITED();                                              \
   InterceptorScope interceptor_scope;                                \
   ret_type res = REAL(func)(s, __VA_ARGS__);                         \