pgsql: Fix several mistaken xreflabel entries, including those spotted

Log Message:
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Fix several mistaken xreflabel entries, including those spotted by
Michael Fuhr.

Modified Files:
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pgsql/doc/src/sgml:
runtime.sgml (r1.294 -> r1.295)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/runtime.sgml.diff?r1=1.294&r2=1.295)