Removed the update of 'TDDCORR' from PERFORM to PERFORMED so that this computation will always be performed if TDDCORR is set to PERFORM.  WJH 
Removed the update of 'TDDCORR' from PERFORM to PERFORMED so that this computation will always be performed if TDDCORR is set to PERFORM.  WJH 


git-svn-id: e4aa3cfa51ba591d1cd1dbbaf7e4a2c2b5d7a7ff@7109 fe389314-cf27-0410-b35b-8c050e845b92

spacetelescope/stsci.tools