ci: Point Windows archives to our own unpacked ones

Author: varungandhi-src

setup_llvm.bzl

@@ -6,9 +6,10 @@ def setup_llvm_toolchain(name):
         "linux-x86_64": {"version": "15.0.6", "triple": "x86_64-linux-gnu-ubuntu-18.04", "sha256": "38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036"},
         "darwin-arm64": {"version": "15.0.6", "triple": "arm64-apple-darwin21.0", "sha256": "32bc7b8eee3d98f72dd4e5651e6da990274ee2d28c5c19a7d8237eb817ce8d91"},
         "darwin-x86_64": {"version": "15.0.7", "triple": "x86_64-apple-darwin21.0", "sha256": "d16b6d536364c5bec6583d12dd7e6cf841b9f508c4430d9ee886726bd9983f1c"},
-        "windows": {"version": "15.0.6", "sha256": "22e2f2c38be4c44db7a1e9da5e67de2a453c5b4be9cf91e139592a63877ac0a2", "url": "https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.6/LLVM-15.0.6-win64.exe"},
+        "windows": {"version": "15.0.6", "sha256": "8c0305c569391fb842c3a1edb07e63a2c0145a2a601d5a87992ae402b437c48f", "url": "https://github.com/sourcegraph/llvm-toolchain-archives/releases/download/v0-20223-04-10/LLVM-15.0.6-win64.tar.xz"},
     }
     llvm_versions, sha256, strip_prefix, urls = {}, {}, {}, {}
+    strip_prefix["windows"] = "LLVM-15.0.6-win64"
     for (k, v) in mapping.items():
         llvm_versions[k] = v["version"]
         sha256[k] = v["sha256"]