message: Implement and expose SQLCancel
diff: @@ -1520,10 +1520,15 @@ SQLRETURN SQL_API EXPORTED_FUNCTION_MAYBE_W(SQLBrowseConnect)(HDBC connection_ha
  return SQL_ERROR;
  }
  -SQLRETURN SQL_API EXPORTED_FUNCTION(SQLCancel)(HSTMT StatementHandle) {
  - LOG(__FUNCTION__ << "Ignoring SQLCancel " << StatementHandle);
  +SQLRETURN SQL_API EXPORTED_FUNCTION(SQLCancel)(
  + SQLHSTMT StatementHandle
  +) {
  + auto func = [&] (Statement & statement) {
  + statement.closeCursor();
  return SQL_SUCCESS;
  - //return SQL_ERROR;
  + };
  +
  + return CALL_WITH_HANDLE(StatementHandle, func);
  }
  SQLRETURN SQL_API EXPORTED_FUNCTION_MAYBE_W(SQLGetCursorName)(
  @@ -1547,7 +1552,7 @@ SQLRETURN SQL_API EXPORTED_FUNCTION(SQLGetFunctions)(HDBC connection_handle, SQL
  SET_EXISTS(SQL_API_SQLBINDPARAMETER);
  //SET_EXISTS(SQL_API_SQLBROWSECONNECT);
  //SET_EXISTS(SQL_API_SQLBULKOPERATIONS);
  - //SET_EXISTS(SQL_API_SQLCANCEL);
  + SET_EXISTS(SQL_API_SQLCANCEL);
  //SET_EXISTS(SQL_API_SQLCANCELHANDLE);
  SET_EXISTS(SQL_API_SQLCLOSECURSOR);
  SET_EXISTS(SQL_API_SQLCOLATTRIBUTE);
  