RTL programs print with their name

RTL programs print with their name

* libguile/print.c (iprin1): Use scm_i_program_print for RTL programs
  too.

* libguile/procprop.c (scm_procedure_name): For RTL programs, call
  scm_i_rtl_program_name if there is no override.

* libguile/programs.h:
* libguile/programs.c (scm_i_rtl_program_name): New helper, dispatches
  to (system vm program).
  (scm_i_program_print): For RTL programs, the fallback prints the code
  pointer too.

* module/system/vm/program.scm (rtl-program-name): Use the debug info to
  get an RTL program name.
  (write-program): Work with RTL programs too.

* test-suite/tests/rtl.test ("procedure name"): Add test.