pgsql: In plpgsql, allow foreign tables to define row types.

In plpgsql, allow foreign tables to define row types.

This seems to have been just an oversight in previous foreign-table work.
A quick grep didn't turn up any other places where RELKIND_FOREIGN_TABLE
was obviously omitted.

One change noted by Alexander Soudakov, the other by me.
Back-patch to 9.1.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/02d88efea1f719e59ce684c2e14bad23d55fdd15

Modified Files
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src/pl/plpgsql/src/pl_comp.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)