message: Avoid redefinition of duckdb_api
diff: #pragma once
  +#ifndef DUCKDB_API
  #ifdef _WIN32
  -#ifdef DUCKDB_BUILD_LIBRARY
  +#if defined(DUCKDB_BUILD_LIBRARY) && !defined(DUCKDB_BUILD_LOADABLE_EXTENSION)
  #define DUCKDB_API __declspec(dllexport)
  #else
  #define DUCKDB_API __declspec(dllimport)
  #else
  #define DUCKDB_API
  #endif
  +#endif
  #include <stdbool.h>
  #include <stdint.h>
  