Fix reading and writing arities into DWARF.

Fix reading and writing arities into DWARF.

* libguile/gsubr.h:
* libguile/gsubr.c (scm_i_primitive_call_ip):
* libguile/programs.c (scm_primitive_call_ip): Adapt to return an
  absolute address.

* module/system/vm/assembler.scm (write-arity-headers): Adapt to write
  byte addresses (relative to the text base).

* module/system/vm/debug.scm (arity-low-pc, arity-high-pc): Return
  absolute addresses, instead of word offsets relative to the text
  base.
  (find-first-arity): Adapt for absolute addresses.

* module/system/vm/program.scm (program-arguments-alist): Adapt for
  arity-low-pc / arity-high-pc absolute addresses.