Re: WIP: dynahash replacement for buffer table

This developed a slight merge conflict.  I've rebased the attached
version, and I also took the step of getting rid of buf_table.c, as I
think I proposed somewhere upthread.  This avoids the overhead of
constructing a BufferTag only to copy it into a BufferLookupEnt, plus
some function calls and so forth.  A quick-and-dirty test suggests
this might not have cut down on the 1-client overhead much, but I
think it's worth doing anyway: it's certainly saving a few cycles, and
I don't think it's complicating anything measurably.

--
Robert Haas
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