[LINST Instrument] Bugfix Date of Death displayed when candidate is still Alive (#7397)

Bugfix to ensure that age at death is only displayed if the candidate has passed away.
This bug only appears in LINST instrument.

Resolves #7396.

Author: jesscall

php/libraries/NDB_BVL_Instrument_LINST.class.inc

@@ -77,7 +77,7 @@ class NDB_BVL_Instrument_LINST extends \NDB_BVL_Instrument
         $this->addBasicDate('Date_taken', 'Date of Administration', $dateOptions);
 
         if (strrpos($this->testName, '_proband') === false) {
-            if ($this->postMortem) {
+            if (!$this->postMortem) {
                 $this->addScoreColumn(
                     'Candidate_Age',
                     'Candidate Age (Months)'