pgsql: The attached patch implements spi_query() and spi_fetchrow()

Log Message:
-----------
The attached patch implements spi_query() and spi_fetchrow() functions
for PL/Perl, to avoid loading the entire result set into memory as the
existing spi_exec_query() function does.

Here's how one might use the new functions:

$x = spi_query("select ...");
while (defined ($y = spi_fetchrow($x))) {
...
return_next(...);
}

The changes do not affect the spi_exec_query() interface in any way.

Abhijit Menon-Sen

Modified Files:
--------------
pgsql/src/pl/plperl:
SPI.xs (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/SPI.xs.diff?r1=1.15&r2=1.16)
plperl.c (r1.81 -> r1.82)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.81&r2=1.82)
spi_internal.h (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/spi_internal.h.diff?r1=1.5&r2=1.6)
pgsql/src/pl/plperl/expected:
plperl.out (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/expected/plperl.out.diff?r1=1.2&r2=1.3)
pgsql/src/pl/plperl/sql:
plperl.sql (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/sql/plperl.sql.diff?r1=1.2&r2=1.3)