Обсуждение: pgsql: Convert the list of syscache names from a series of #define's

Log Message:
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Convert the list of syscache names from a series of #define's into an enum,
to avoid the pain of manually renumbering them anytime we insert another
name in alphabetical order.  An excellent idea from Alex Hunsaker and
NikhilS' inherited-constraints patch --- whether or not the rest of that
gets in, this should.  Dunno why we never thought of it before.

Modified Files:
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    pgsql/src/include/utils:
        syscache.h (r1.71 -> r1.72)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/syscache.h?r1=1.71&r2=1.72)