pgsql: Fix *-qualification of named parameters in SQL-language function

Fix *-qualification of named parameters in SQL-language functions.

Given a composite-type parameter named x, "$1.*" worked fine, but "x.*"
not so much.  This has been broken since named parameter references were
added in commit 9bff0780cf5be2193a5bad0d3df2dbe143085264, so patch back
to 9.2.  Per bug #9085 from Hardy Falk.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/888b5657049f56508645be4f5dd911b2c286438c

Modified Files
--------------
src/backend/executor/functions.c       |    8 ++++++
src/test/regress/expected/rowtypes.out |   47 ++++++++++++++++++++++++++++++++
src/test/regress/sql/rowtypes.sql      |   28 +++++++++++++++++++
3 files changed, 83 insertions(+)