pgsql: Fix psql \h output for case of no parameters (ie, list all the - Mailing list pgsql-committers

Log Message:
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Fix psql \h output for case of no parameters (ie, list all the known commands)
to format properly for the actually needed column width, instead of having
a hard-wired assumption about the longest command name length.  Also make it
respond to the current screen width.  In passing, const-ify the constant
table.

Modified Files:
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    pgsql/src/bin/psql:
        create_help.pl (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/create_help.pl?r1=1.16&r2=1.17)
        help.c (r1.121 -> r1.122)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/help.c?r1=1.121&r2=1.122)