pgsql: Repair problems with the result of lookup_rowtype_tupdesc()

Log Message:
-----------
Repair problems with the result of lookup_rowtype_tupdesc() possibly being
discarded by cache flush while still in use.  This is a minimal patch that
just copies the tupdesc anywhere it could be needed across a flush.  Applied
to back branches only; Neil Conway is working on a better long-term solution
for HEAD.

Tags:
----
REL8_0_STABLE

Modified Files:
--------------
    pgsql/src/backend/access/heap:
        tuptoaster.c (r1.47 -> r1.47.4.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/tuptoaster.c.diff?r1=1.47&r2=1.47.4.1)
    pgsql/src/backend/parser:
        parse_coerce.c (r2.126.4.1 -> r2.126.4.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_coerce.c.diff?r1=2.126.4.1&r2=2.126.4.2)
        parse_target.c (r1.129.4.1 -> r1.129.4.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_target.c.diff?r1=1.129.4.1&r2=1.129.4.2)
    pgsql/src/backend/utils/adt:
        rowtypes.c (r1.8.4.2 -> r1.8.4.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/rowtypes.c.diff?r1=1.8.4.2&r2=1.8.4.3)
        ruleutils.c (r1.188.4.2 -> r1.188.4.3)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ruleutils.c.diff?r1=1.188.4.2&r2=1.188.4.3)
    pgsql/src/backend/utils/cache:
        typcache.c (r1.11 -> r1.11.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/cache/typcache.c.diff?r1=1.11&r2=1.11.4.1)
    pgsql/src/pl/plperl:
        plperl.c (r1.67.4.4 -> r1.67.4.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.67.4.4&r2=1.67.4.5)
    pgsql/src/pl/plpgsql/src:
        pl_exec.c (r1.127.4.4 -> r1.127.4.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c.diff?r1=1.127.4.4&r2=1.127.4.5)
    pgsql/src/pl/plpython:
        plpython.c (r1.58.4.4 -> r1.58.4.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c.diff?r1=1.58.4.4&r2=1.58.4.5)
    pgsql/src/pl/tcl:
        pltcl.c (r1.94 -> r1.94.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/pltcl.c.diff?r1=1.94&r2=1.94.4.1)