llvm-project

a88e6558 - [llvm] build Blake3 source with LLVM_EXPORTS defined (#144753)

[llvm] build Blake3 source with LLVM_EXPORTS defined (#144753) ## Purpose This patch ensures that the BLAKE3 implementation in the LLVM Support library exports its public interface with `__declspec(dllexport)` when building LLVM as a Windows DLL. ## Background The effort to support building LLVM as a Windows DLL is tracked in #109483. Additional context is provided in [this discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307). ## Overview Replicate [this logic](https://github.com/llvm/llvm-project/blob/main/llvm/cmake/modules/AddLLVM.cmake#L662-L664) from `llvm_add_library()` for the `LLVMSupportBlake3` target. Without this change, the `llvm_blake_` functions will only be annotated with `__declspec(dllimport)` when building LLVM as a Windows DLL which leads to inconsistent DLL linkage warnings from MSVC and `clang-cl`.