Repair broken SizeDumpVnode

Since ever vn_length_hi vos not taken into account. Also for
OSD-files the size of the metadata was not added. The new version
is now exact within 80 bytes which is much better than before:
A certain volume with 9.255 TB net data was calculated to 1.8 TB!
Two minor bug fixes

at one #if defined the brackets were missing and
NewTrans doesn't return a struct NewTrans*, but a struct volser_trans*!