export AOTI_TORCH_EXPORT on Windows. (pytorch#140030)

Fixes pytorch#139954

reproduce UT:
```cmd
pytest test/inductor/test_torchinductor_codegen_dynamic_shapes.py -k test_device_assert_dynamic_shapes_cpu
```
Issue:
<img width="856" alt="image" src="https://github.com/user-attachments/assets/5fc501a9-54e5-45ac-9fb3-509ec11a7abe">

After fixing:
![Image](https://github.com/user-attachments/assets/883846fb-8e92-4b9c-9400-daab32382a3a)

Pull Request resolved: pytorch#140030
Approved by: https://github.com/jgong5, https://github.com/desertfire

Author: xuhancn

caffe2/CMakeLists.txt

@@ -779,6 +779,7 @@ endif()
 
 if(NOT BUILD_LIBTORCHLESS)
 add_library(torch_cpu ${Caffe2_CPU_SRCS})
+target_compile_definitions(torch_cpu PRIVATE -DEXPORT_AOTI_FUNCTIONS)
 if(HAVE_SOVERSION)
   set_target_properties(torch_cpu PROPERTIES
       VERSION ${TORCH_VERSION} SOVERSION ${TORCH_SOVERSION})
@@ -963,6 +964,7 @@ elseif(USE_CUDA)
   set(CUDA_LINK_LIBRARIES_KEYWORD)
   torch_compile_options(torch_cuda)  # see cmake/public/utils.cmake
   target_compile_definitions(torch_cuda PRIVATE USE_CUDA)
+  target_compile_definitions(torch_cuda PRIVATE -DEXPORT_AOTI_FUNCTIONS)
 
   if(USE_CUFILE)
     target_link_libraries(torch_cuda PRIVATE torch::cufile)
@@ -1053,6 +1055,7 @@ if(USE_XPU)
   add_library(torch_xpu ${Caffe2_XPU_SRCS})
   torch_compile_options(torch_xpu)  # see cmake/public/utils.cmake
   target_compile_definitions(torch_xpu PRIVATE USE_XPU)
+  target_compile_definitions(torch_xpu PRIVATE -DEXPORT_AOTI_FUNCTIONS)
   if(WIN32)
     target_compile_options(torch_xpu PRIVATE /permissive-)
   endif()

torch/csrc/inductor/aoti_torch/c/shim.h

@@ -44,8 +44,11 @@
 // to symbol clashes at link time if libtorch is included in a DLL and binary
 // that depends on the DLL. As a short term fix, we don't export the symbols.
 // In the long term, this will need to be addressed when Windows is supported.
-// #define AOTI_TORCH_EXPORT __declspec(dllexport)
-#define AOTI_TORCH_EXPORT
+#ifdef EXPORT_AOTI_FUNCTIONS
+#define AOTI_TORCH_EXPORT __declspec(dllexport)
+#else
+#define AOTI_TORCH_EXPORT __declspec(dllimport)
+#endif
 #else // !_WIN32
 #define AOTI_TORCH_EXPORT
 #endif // _WIN32