plpsm - plpgpsm: For declared cursor in block is used unnamed portal,

Log Message:
-----------
For declared cursor in block is used unnamed portal, and for identification
isn't used name but portal pointer. It solve problem with nested block with
local cursor's declaration not unique name as outer declared cursor. Named
portals are supported still for refcursors.

Opened portal identified by portal pointer is automaticly closed when block is
finalised. We cannot solve closing portals when is exception, because rollback
to savepoint close all opened portals from nested blocks.

Modified Files:
--------------
    plpgpsm/src:
        pl_exec.c (r1.22 -> r1.23)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/pl_exec.c.diff?r1=1.22&r2=1.23)
        plpgpsm.h (r1.19 -> r1.20)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plpsm/plpgpsm/src/plpgpsm.h.diff?r1=1.19&r2=1.20)