Fix Windows CI linking failures.

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "externals/llvm-project"]
 	path = externals/llvm-project
-	url = https://github.com/llvm/llvm-project.git
+	url = https://github.com/iree-org/llvm-project.git
 [submodule "externals/stablehlo"]
 	path = externals/stablehlo
 	url = https://github.com/openxla/stablehlo.git

python/CMakeLists.txt

@@ -117,6 +117,15 @@ add_mlir_python_common_capi_library(TorchMLIRAggregateCAPI
   DECLARED_SOURCES ${_source_components}
 )
 
+# On Windows, we disabled object libraries for aggregate targets (see AddMLIR.cmake patch).
+# The patch makes AddMLIR.cmake use /WHOLEARCHIVE instead of object libraries on Windows.
+if(WIN32)
+  # WINDOWS_EXPORT_ALL_SYMBOLS doesn't work without source files.
+  # We keep it OFF and let the empty exports.def be used.
+  # The /WHOLEARCHIVE linked libraries should export their symbols if they're built as SHARED.
+  set_target_properties(TorchMLIRAggregateCAPI PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS OFF)
+endif()
+
 add_mlir_python_modules(TorchMLIRPythonModules
   ROOT_PREFIX "${TORCH_MLIR_PYTHON_PACKAGES_DIR}/torch_mlir/torch_mlir"
   INSTALL_PREFIX "python_packages/torch_mlir/torch_mlir"