[compiler-rt] Changes to support running tests for Windows arm64 asan (PR #66973)

[Omair Javaid via llvm-commits]

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@@ -462,7 +462,7 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
   return 4;
 #endif
 
-#if SANITIZER_WINDOWS64
+#if SANITIZER_WINDOWSx64
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omjavaid wrote:

Kindly add a comment on why this is x64 only.

https://github.com/llvm/llvm-project/pull/66973