ci: Skip testing LLVM on Windows

Do not run distribution bundle tests for Zephyr SDK LLVM toolchain on
Windows because there are known issues causing strange CMake behaviours
and subsequent build failures (see GitHub issue #831).

Revert this commit when the above issue is fixed.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

.github/workflows/ci.yml

@@ -1787,6 +1787,13 @@ jobs:
             "
         fi
 
+        # FIXME: Skip testing for LLVM on Windows because there are known issues
+        # (see GitHub issue #831).
+        if [ "${{ matrix.toolchain }}" == "llvm" ] &&
+           [ "${{ runner.os }}" == "Windows" ]; then
+          exit 0
+        fi
+
         # Set toolchain variant
         export ZEPHYR_TOOLCHAIN_VARIANT=zephyr-${{ matrix.toolchain }}