function in a dynamic object.
(scm_dynamic_call, scm_dynamic_args_call): Accept the values
produced by scm_dynamic_func as the thing to call.
* dynl.c, dynl-dl.c, dynl-dld.c, dynl-shl.c: Restructured.
(scm_register_module_xxx, scm_registered_modules,
scm_clear_registered_modules): New functions.