修复编译错误

https://git.gnome.org/browse/dia/commit/?id=0b863adcad031c70601e375d72dae64fdd967752
修复编译错误

https://git.gnome.org/browse/dia/commit/?id=0b863adcad031c70601e375d72dae64fdd967752
Merge pull request #66 from jiangtao9999/master

修复编译错误