ggml : fix Windows build

ggml.c

@@ -37,7 +37,7 @@ typedef HANDLE pthread_t;
 
 typedef DWORD thread_ret_t;
 static int pthread_create(pthread_t* out, void* unused, thread_ret_t(*func)(void*), void* arg) {
-    HANDLE handle = CreateThread(NULL, 0, func, arg, 0, NULL);
+    HANDLE handle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE) func, arg, 0, NULL);
     if (handle == NULL)
     {
         return EAGAIN;