pgsql: Remove code that attempted to rename index columns to keep them

Log Message:
-----------
Remove code that attempted to rename index columns to keep them in sync with
their underlying table columns.  That code was not bright enough to cope with
collision situations (ie, new name conflicts with some other column of the
index).  Since there is no functional reason to do this at all, trying to
upgrade the logic to be bulletproof doesn't seem worth the trouble.

This change means that both the index name and the column names of an index
are set when it's created, and won't be automatically changed when the
underlying table columns are renamed.  Neatnik DBAs are still free to rename
them manually, of course.

Modified Files:
--------------
    pgsql/src/backend/commands:
        tablecmds.c (r1.310 -> r1.311)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablecmds.c?r1=1.310&r2=1.311)