srfi-11.scm, srfi-14.scm, srfi-16.scm: Move module the system
directives `export', `export-syntax', `re-export' and
`re-export-syntax' into the `define-module' form. This is the
recommended way of exporting bindings.
* srfi-14.c (scm_char_set_ref, scm_char_set_cursor_next,
scm_end_of_char_set_p): reject negative cursor values.
(scm_list_to_char_set, scm_list_to_char_set_x): when reporting
type error in list component, omit the position (was always 1).
* srfi-19.scm, srfi-17.scm, srfi-16.scm, srfi-14.scm, srfi-13.scm,
srfi-11.scm, srfi-10.scm, srfi-9.scm, srfi-8.scm, srfi-6.scm,
srfi-2.scm: Use `cond-expand-provide' for providing features to
`cond-expand'.