add missing libwpd_internal for gsf endianness casts
add missing libwpd_internal for gsf endianness casts

cpjreynolds/libwpd,cpjreynolds/libwpd,Distrotech/librevenge,Distrotech/librevenge,Distrotech/libpwd,Distrotech/librevenge,cpjreynolds/libwpd,Distrotech/librevenge,Distrotech/libpwd,Distrotech/libpwd,Distrotech/libpwd,Distrotech/librevenge