cond-expand srfi-6 string ports

[Kevin Ryde]

Since srfi-6 string ports are builtin to guile, should srfi-6 be
always true in cond-expand?  Ie. true before doing any use-module?

I don't suppose it makes much difference, but if the feature is
available it may as well be indicated.

        * boot-9.scm (%cond-expand-features): Add srfi-6 which is in the core.

(This could be for the 1.6 branch too.)

--- boot-9.scm.~1.332.~ 2004-06-17 08:08:25.000000000 +1000
+++ boot-9.scm  2004-07-05 09:47:14.000000000 +1000
@@ -3183,14 +3183,18 @@
 ;;;
 ;;; Currently, the following feature identifiers are supported:
 ;;;
-;;;   guile r5rs srfi-0
+;;;   guile r5rs srfi-0 srfi-6
 ;;;
 ;;; Remember to update the features list when adding more SRFIs.
 ;;;
 
 (define %cond-expand-features
   ;; Adjust the above comment when changing this.
-  '(guile r5rs srfi-0))
+  '(guile
+    r5rs
+    srfi-0   ;; cond-expand itself
+    srfi-6   ;; open-input-string etc, in the guile core
+    ))
 
 ;; This table maps module public interfaces to the list of features.
 ;;