(build_signature_method_call): Renamed offset_identifier and local variable offset to vt_off_identifer and vt_off...
(build_signature_method_call): Renamed offset_identifier and
local variable offset to vt_off_identifer and vt_off, respecitively.
(build_signature_table_constructor): Renamed offset to vt_off.
(build_signature_table_constructor): Build the constructor
according to the new layout. Set the vb_off field to -1 for now.