pgsql: Fix incorrect logic in plpgsql for cleanup after evaluation of

Log Message:
-----------
Fix incorrect logic in plpgsql for cleanup after evaluation of non-simple
expressions.  We need to deal with this when handling subscripts in an array
assignment, and also when catching an exception.  In an Assert-enabled build
these omissions led to Assert failures, but I think in a normal build the
only consequence would be short-term memory leakage; which may explain why
this wasn't reported from the field long ago.

Back-patch to all supported versions.  7.4 doesn't have exceptions, but
otherwise these bugs go all the way back.

Heikki Linnakangas and Tom Lane

Tags:
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REL8_2_STABLE

Modified Files:
--------------
    pgsql/src/pl/plpgsql/src:
        pl_exec.c (r1.180.2.13 -> r1.180.2.14)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c?r1=1.180.2.13&r2=1.180.2.14)
    pgsql/src/test/regress/expected:
        plpgsql.out (r1.51 -> r1.51.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/plpgsql.out?r1=1.51&r2=1.51.2.1)
    pgsql/src/test/regress/sql:
        plpgsql.sql (r1.44 -> r1.44.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/plpgsql.sql?r1=1.44&r2=1.44.2.1)