[llvm] [llvm] Add API to get decompressed size of a zstd compressed buffer. (PR #107020)

[Fangrui Song via llvm-commits]

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@@ -224,6 +224,20 @@ Error zstd::decompress(ArrayRef<uint8_t> Input,
   return E;
 }
 
+Error zstd::getDecompressedSize(ArrayRef<uint8_t> Input,
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MaskRay wrote:

more conventional to return `Expected<uint64_t>` and avoid output parameter

https://github.com/llvm/llvm-project/pull/107020