- Common Lisp multiple values, required for specifier improvements.

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The multiple return values from get-specifier should allow the
specifier value to be modified in the correct fashion (i.e.  should
interact correctly with all manner of changes from other callers)
using set-specifier.  We should check this and see if we need other
return values.  (how-to-add? inst-list?)

In C, call multiple-values-context to get number of expected values,
and multiple-value-set (#, value) to get values other than the first.

(Returns Qno_value, or something, if there are no values.

#### Or should throw?  Probably not.
#### What happens if a fn returns no values but the caller expects a
#### value?

Something like funcall_with_multiple_values() for setting up the
context.

For efficiency, byte code could notice Ffuncall to m.v. functions and
sub in special opcodes during load in processing, if it mattered.
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