squish to primitive reification

* test-suite/tests/tree-il.test: Update for primitive-ref reification
  fix.
Re-add the list hack to compile-cps

* module/language/tree-il/compile-cps.scm (convert): Re-add the list
  hack.  Ideally these go into some tree-il pass.
fix make-long-immediate, make-long-long-immediate for dst >= 256

* libguile/vm-engine.c (make-long-immediate, make-long-long-immediate):
  Fix declaration of "dst" variable.
asm-labels is a hash table

* module/system/vm/assembler.scm (make-assembler, label):
  (link-data, process-relocs, process-labels): Change labels to be a
  hash table.
fix docstring assembly and fetching

* module/system/vm/assembler.scm (link-docstrs): Write pc offsets as
  byte addresses.  Works better with native code.
* module/system/vm/debug.scm (find-program-docstring): Fix the linear
  search.  How embarassing!