Deprecate Buffers.

[NotFound]

> Currently we have STRING and Buffers as one of core GCable objects.
> Buffers were introduced long time ago, before ByteBuffer PMC. At this
> point of Buffers used only in Packfiles and can be easiliy replaced
> with BytBuffer.

Note that ByteBuffer, as its name implies, provides only byte
addressing. If you plan to extend heavily its interface, will be
better to add a new general purpose buffer PMC, IMO.

-- 
Salu2