pgsql: Move NAMEDATALEN definition from postgres_ext.h to

Log Message:
-----------
Move NAMEDATALEN definition from postgres_ext.h to pg_config_manual.h. It
used to be part of libpq's exported interface many releases ago, but now
it's no longer necessary to make it accessible to clients.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        syntax.sgml (r1.114 -> r1.115)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/syntax.sgml.diff?r1=1.114&r2=1.115)
    pgsql/src/backend/catalog:
        Makefile (r1.61 -> r1.62)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/Makefile.diff?r1=1.61&r2=1.62)
        genbki.sh (r1.41 -> r1.42)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/genbki.sh.diff?r1=1.41&r2=1.42)
    pgsql/src/include:
        pg_config_manual.h (r1.23 -> r1.24)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pg_config_manual.h.diff?r1=1.23&r2=1.24)
        postgres_ext.h (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/postgres_ext.h.diff?r1=1.16&r2=1.17)
    pgsql/src/tools/msvc:
        genbki.pl (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/genbki.pl.diff?r1=1.2&r2=1.3)