fixed windows build

csrc/convert.cpp

+#include <Python.h>
 #include <torch/script.h>
 
 #include "cpu/convert_cpu.h"
@@ -6,6 +7,10 @@
 #include "cuda/convert_cuda.h"
 #endif
 
+#ifdef _WIN32
+PyMODINIT_FUNC PyInit__convert(void) { return NULL; }
+#endif
+
 torch::Tensor ind2ptr(torch::Tensor ind, int64_t M) {
   if (ind.device().is_cuda()) {
 #ifdef WITH_CUDA

csrc/diag.cpp

+#include <Python.h>
 #include <torch/script.h>
 
 #include "cpu/diag_cpu.h"
@@ -6,6 +7,10 @@
 #include "cuda/diag_cuda.h"
 #endif
 
+#ifdef _WIN32
+PyMODINIT_FUNC PyInit__diag(void) { return NULL; }
+#endif
+
 torch::Tensor non_diag_mask(torch::Tensor row, torch::Tensor col, int64_t M,
                             int64_t N, int64_t k) {
   if (row.device().is_cuda()) {

csrc/spmm.cpp

+#include <Python.h>
 #include <torch/script.h>
 
 #include "cpu/spmm_cpu.h"
@@ -6,6 +7,10 @@
 #include "cuda/spmm_cuda.h"
 #endif
 
+#ifdef _WIN32
+PyMODINIT_FUNC PyInit__spmm(void) { return NULL; }
+#endif
+
 std::tuple<torch::Tensor, torch::optional<torch::Tensor>>
 spmm_fw(torch::Tensor rowptr, torch::Tensor col,
         torch::optional<torch::Tensor> optional_value, torch::Tensor mat,

csrc/spspmm.cpp

+#include <Python.h>
 #include <torch/script.h>
 
 #include "cpu/spspmm_cpu.h"
@@ -6,6 +7,10 @@
 #include "cuda/spspmm_cuda.h"
 #endif
 
+#ifdef _WIN32
+PyMODINIT_FUNC PyInit__spspmm(void) { return NULL; }
+#endif
+
 std::tuple<torch::Tensor, torch::Tensor, torch::optional<torch::Tensor>>
 spspmm_sum(torch::Tensor rowptrA, torch::Tensor colA,
            torch::optional<torch::Tensor> optional_valueA,