pgsql: Fix plperl crash with list value return for an array result type.

Log Message:
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Fix plperl crash with list value return for an array result type.
Reported by Michael Fuhr, fixed by Andrew Dunstan.

Modified Files:
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pgsql/src/pl/plperl:
plperl.c (r1.85 -> r1.86)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.85&r2=1.86)