pgsql: Fix up plperl 'use_strict' so that it can be enabled or disabled

Log Message:
-----------
Fix up plperl 'use_strict' so that it can be enabled or disabled on the
fly.  Fix problem with incompletely duplicated setup code.  Andrew Dunstan,
from an idea of Michael Fuhr's.

Modified Files:
--------------
    pgsql/src/pl/plperl:
        plperl.c (r1.90 -> r1.91)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.90&r2=1.91)
    pgsql/src/pl/plperl/expected:
        plperl_elog.out (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/expected/plperl_elog.out.diff?r1=1.2&r2=1.3)
    pgsql/src/pl/plperl/sql:
        plperl_elog.sql (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/sql/plperl_elog.sql.diff?r1=1.1&r2=1.2)