SAV writer: Fix Variable Display Parameter w/ long strings
SAV writer: Fix Variable Display Parameter w/ long strings

The Variable Display Parameter record contains information about
ordinality and text alignment. Previously, one entry was emitted for
each real variable. However, SPSS emits an entry for ghost variables as
well. This change mimics the SPSS behavior, and possibly fixes
tidyverse/haven#266

WizardMac/ReadStat,WizardMac/ReadStat