add special case for (apply values ...)
* libguile/vm-engine.c (vm_run): Move nvalues to the top level, to avoid
(spurious, it seems) gcc warnings about it being used uninitialized.
* libguile/vm-i-system.c (halt, return/values): Adapt to gcc silliness.
Deindent some of return/values.
(return/values*): New instruction, does what (apply values . args)
would do.
* module/language/scheme/translate.scm (custom-transformer-table): Move
the apply and @apply cases here from inline.scm, because we need some
more cleverness when dealing with cases like (apply values . args).
(lookup-apply-transformer): Define an eval transformer for `values',
turning it into ghil-values*.
* module/system/il/compile.scm (codegen): Compile <ghil-values*> into
return/values*.
* module/system/il/ghil.scm: Add <ghil-values*> and accessors.
(ghil-lookup): Add optional argument, define?, which if false tells us
not to actually cache the binding if it is not found in the toplevel.
* module/system/il/inline.scm: Remove apply clauses.
* module/system/vm/frame.scm (bootstrap-frame?): Update heuristic for
bootstrap-frame?, as the bootstrap frame is now 5 bytes since it
accepts multiple values.