Add project files

breeze/cmake/toolchains/windows-arm64-clang.cmake

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+# windows-arm64-clang: Clang with its own GNU-style driver (clang++) building
+# for ARM64 Windows, as in an MSYS2 CLANGARM64 shell. Not clang-cl -- see
+# windows-arm64-clang-cl for that.
+#
+# Nothing is pinned: the CLANGARM64 environment is what makes clang++ target
+# ARM64 with the mingw ABI. TargetSelection.cmake checks that afterwards.
+#
+# See _common.cmake (pmn_msys_clang_toolchain).
+include("${CMAKE_CURRENT_LIST_DIR}/_common.cmake")
+
+pmn_toolchain_target("windows-arm64-clang")
+pmn_msys_clang_toolchain()