* module/ice-9/boot-9.scm (%cond-expand-features): Remove redundant list
of feature identifiers in the comment. Explain more clearly what
belongs in this list. Remove srfi-6.
* module/srfi/srfi-4.scm, module/srfi/srfi-27.scm,
module/srfi/srfi-31.scm, module/srfi/srfi-38.scm,
module/srfi/srfi-39.scm, module/srfi/srfi-42.scm,
module/srfi/srfi-45.scm, module/srfi/srfi-67.scm: Add missing
'cond-expand-provide'.
* module/srfi/srfi-69.scm: Fix erroneous 'cond-expand-provide'.
* doc/ref/srfi-modules.texi (SRFI-0): Update the list of features in
Guile core.
* module/srfi/srfi-69.scm: Move the macros up before the functions that
use them, so that the compiler can do its job.
(hash-table-walk): While it is true about what I said about R5RS
before, it seems that for R6 this will have to change. Anyway. In the
meantime, since the test suite checks that hash-table-walk procedures'
return values and number of return values are ignored, call that
procedure within a call-with-values.
