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)