pgsql-server: Add: < > * Use a phantom command counter for nested

Log Message:
-----------
Add:

<

* Use a phantom command counter for nested subtransactions to reduce
tuple overhead

Modified Files:
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pgsql-server/doc:
TODO (r1.1290 -> r1.1291)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/TODO.diff?r1=1.1290&amp;r2=1.1291)