[compiler-rt][ASan] Define SANITIZER_INTERCEPT_WCSNLEN (llvm#164845)

Follow up to llvm#162028

`SANITIZER_INTERCEPT_WCSNLEN` is not defined, so `internal_wcsnlen` is
always used instead of using `REAL(wcsnlen)` if intercepted.

Author: zacklj89

compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h

@@ -551,6 +551,7 @@ SANITIZER_WEAK_IMPORT void *aligned_alloc(__sanitizer::usize __alignment,
 #define SANITIZER_INTERCEPT_MALLOC_USABLE_SIZE (!SI_MAC && !SI_NETBSD)
 #define SANITIZER_INTERCEPT_MCHECK_MPROBE SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_WCSLEN 1
+#define SANITIZER_INTERCEPT_WCSNLEN 1
 #define SANITIZER_INTERCEPT_WCSCAT (SI_POSIX || SI_WINDOWS)
 #define SANITIZER_INTERCEPT_WCSDUP SI_POSIX
 #define SANITIZER_INTERCEPT_SIGNAL_AND_SIGACTION (!SI_WINDOWS && SI_NOT_FUCHSIA)