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_1_STABLE

Modified Files:
--------------
    pgsql/src/backend/access/heap:
        tuptoaster.c (r1.53.2.2 -> r1.53.2.3)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/tuptoaster.c.diff?r1=1.53.2.2&r2=1.53.2.3)
    pgsql/src/backend/parser:
        parse_coerce.c (r2.132.2.2 -> r2.132.2.3)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_coerce.c.diff?r1=2.132.2.2&r2=2.132.2.3)
        parse_target.c (r1.138.2.1 -> r1.138.2.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_target.c.diff?r1=1.138.2.1&r2=1.138.2.2)
    pgsql/src/backend/utils/adt:
        rowtypes.c (r1.13 -> r1.13.2.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/rowtypes.c.diff?r1=1.13&r2=1.13.2.1)
        ruleutils.c (r1.207.2.3 -> r1.207.2.4)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ruleutils.c.diff?r1=1.207.2.3&r2=1.207.2.4)
    pgsql/src/backend/utils/cache:
        typcache.c (r1.15.2.1 -> r1.15.2.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/cache/typcache.c.diff?r1=1.15.2.1&r2=1.15.2.2)
    pgsql/src/backend/utils/fmgr:
        funcapi.c (r1.26 -> r1.26.2.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/fmgr/funcapi.c.diff?r1=1.26&r2=1.26.2.1)
    pgsql/src/pl/plperl:
        plperl.c (r1.94.2.2 -> r1.94.2.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.94.2.2&r2=1.94.2.3)
    pgsql/src/pl/plpgsql/src:
        pl_exec.c (r1.154.2.2 -> r1.154.2.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpgsql/src/pl_exec.c.diff?r1=1.154.2.2&r2=1.154.2.3)
    pgsql/src/pl/plpython:
        plpython.c (r1.66.2.2 -> r1.66.2.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plpython/plpython.c.diff?r1=1.66.2.2&r2=1.66.2.3)
    pgsql/src/pl/tcl:
        pltcl.c (r1.98.2.1 -> r1.98.2.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/tcl/pltcl.c.diff?r1=1.98.2.1&r2=1.98.2.2)