Foreign procedures are RTL programs
* libguile/foreign.c: Convert to using RTL stubs. Because RTL code has
different GC characteristics than objcode -- it's mostly assumed that
RTL code will never go away -- we go ahead and pre-generate code for
100 arguments. This is actually less memory than the stack VM code,
and doesn't require any relocations at load-time: bonus! We'll cross
the >=100 args bridge if we ever come to it.
(get_foreign_stub_code) New function.
(scm_i_foreign_arity): New helper, like scm_i_primitive_arity.
(cif_to_procedure): Rework to make RTL programs.
* libguile/foreign.h: Declare scm_pointer_to_scm and
scm_scm_to_pointer. Declare new internal helpers.
* libguile/gsubr.c (create_subr): Refactor to set the flags when the
object is allocated.
* libguile/instructions.h: Define SCM_PACK_RTL_12_12.
* libguile/programs.c (scm_i_rtl_program_minimum_arity): Dispatch to
scm_i_foreign_arity if the procedure has the FOREIGN flag.
* libguile/programs.h (SCM_F_PROGRAM_IS_FOREIGN)
(SCM_PROGRAM_IS_FOREIGN): New interfaces.
* test-suite/tests/foreign.test ("procedure->pointer"): Add a test for
foreign arities.