pgsql: Eliminate memory leaks in plperl's spi_prepare() function.

Eliminate memory leaks in plperl's spi_prepare() function.

Careless use of TopMemoryContext for I/O function data meant that repeated
use of spi_prepare and spi_freeplan would leak memory at the session level,
as per report from Christian Schröder. In addition, spi_prepare
leaked a lot of transient data within the current plperl function's SPI
Proc context, which would be a problem for repeated use of spi_prepare
within a single plperl function call; and it wasn't terribly careful
about releasing permanent allocations in event of an error, either.

In passing, clean up some copy-and-pasteos in query-lookup error messages.

Alex Hunsaker and Tom Lane

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/0fe397fa49559f78d2cbffa6f2422d65d9e0e143

Modified Files
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src/pl/plperl/plperl.c | 116 ++++++++++++++++++++++++++++++------------------
1 files changed, 72 insertions(+), 44 deletions(-)