pgsql: Avoid referring to a specific version of the SQL standard except

Log Message:
-----------
Avoid referring to a specific version of the SQL standard except where
necessary, and be careful to refer to the right version where it is
useful to do so. This partially reverts an ill-considered search and
replace from a few months ago.

Modified Files:
--------------
pgsql/doc/src/sgml:
array.sgml (r1.44 -> r1.45)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/array.sgml.diff?r1=1.44&r2=1.45)
ddl.sgml (r1.47 -> r1.48)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ddl.sgml.diff?r1=1.47&r2=1.48)
ecpg.sgml (r1.69 -> r1.70)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ecpg.sgml.diff?r1=1.69&r2=1.70)
errcodes.sgml (r1.14 -> r1.15)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/errcodes.sgml.diff?r1=1.14&r2=1.15)
func.sgml (r1.289 -> r1.290)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.289&r2=1.290)
intro.sgml (r1.29 -> r1.30)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/intro.sgml.diff?r1=1.29&r2=1.30)