Add srfi-16 and srfi-30 to %cond-expand-features.

Add srfi-16 and srfi-30 to %cond-expand-features.

* module/ice-9/boot-9.scm (%cond-expand-features): Add srfi-16 and
  srfi-30.

* doc/ref/srfi-modules.texi (SRFI-0): Add srfi-16 and srfi-30 to the
  list of core features.

* module/srfi/srfi-16.scm: Remove call to 'cond-expand-provide'.