WIP: github: Run test-libcxx, test-openmp and test-compiler-rt standalone

.github/workflows/build.yml

@@ -19,7 +19,7 @@ jobs:
   # slightly more, when we know a separate build of the same version but with
   # assertions enabled, has passed some amount of tests.
   prepare:
-    if: (github.event_name != 'schedule') || (github.repository == 'mstorsjo/llvm-mingw')
+    if: false
     runs-on: ubuntu-latest
     outputs:
       LLVM_VERSION: ${{steps.get-versions.outputs.LLVM_VERSION}}
@@ -499,7 +499,6 @@ jobs:
     # testing with the latest compiler instead of an older release).
     # Therefore, keep the test disabled by default; it's easy to enable
     # temporarily on a branch for testing.
-    needs: [linux-cross-windows, prepare]
     strategy:
       fail-fast: false
       matrix:
@@ -509,11 +508,9 @@ jobs:
           - { arch: aarch64, target_arch: aarch64 }
     runs-on: ${{startsWith(matrix.arch, 'a') && 'windows-11-arm' || 'windows-latest'}}
     steps:
-      - uses: actions/download-artifact@v4
-        with:
-          name: windows-ucrt-${{matrix.arch}}-toolchain
       - name: Unpack toolchain
         run: |
+          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20251202/llvm-mingw-20251202-ucrt-${{matrix.arch}}.zip
           Expand-Archive llvm-mingw-*.zip -DestinationPath .
           del llvm-mingw-*.zip
           mv llvm-mingw-* c:\llvm-mingw
@@ -557,7 +554,6 @@ jobs:
   # This also forces testing the bundled python executables.
   test-openmp:
     # Only running these tests in scheduled builds.
-    needs: [linux-cross-windows, prepare]
     strategy:
       fail-fast: false
       matrix:
@@ -567,11 +563,9 @@ jobs:
           - { arch: aarch64 }
     runs-on: ${{startsWith(matrix.arch, 'a') && 'windows-11-arm' || 'windows-latest'}}
     steps:
-      - uses: actions/download-artifact@v4
-        with:
-          name: windows-ucrt-${{matrix.arch}}-toolchain
       - name: Unpack toolchain
         run: |
+          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20251202/llvm-mingw-20251202-ucrt-${{matrix.arch}}.zip
           Expand-Archive llvm-mingw-*.zip -DestinationPath .
           del llvm-mingw-*.zip
           mv llvm-mingw-* c:\llvm-mingw
@@ -619,7 +613,6 @@ jobs:
   # also forces testing the bundled python executables.
   test-compiler-rt:
     # Only running these tests in scheduled builds.
-    needs: [linux-cross-windows, prepare]
     strategy:
       fail-fast: false
       matrix:
@@ -629,11 +622,9 @@ jobs:
           - aarch64
     runs-on: ${{startsWith(matrix.arch, 'a') && 'windows-11-arm' || 'windows-latest'}}
     steps:
-      - uses: actions/download-artifact@v4
-        with:
-          name: windows-ucrt-${{matrix.arch}}-toolchain
       - name: Unpack toolchain
         run: |
+          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20251202/llvm-mingw-20251202-ucrt-${{matrix.arch}}.zip
           Expand-Archive llvm-mingw-*.zip -DestinationPath .
           del llvm-mingw-*.zip
           mv llvm-mingw-* c:\llvm-mingw