add LIBCITYGML_EXPORT on getCityObjectsTypeMaskFromString prototype
add LIBCITYGML_EXPORT on getCityObjectsTypeMaskFromString prototype

tectronics/libcitygml,terencechill/libcitygml,yangqiaosheng/libcitygml,flyskyosg/libcitygml,jpouderoux/libcitygml