Avoid calling display when processing sxml

As I think this could cause suspendable ports issues.

guix-data-service/web/sxml.scm

@@ -29,6 +29,7 @@
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:use-module (ice-9 hash-table)
+  #:use-module (ice-9 textual-ports)
   #:export (sxml->html))
 
 (define %self-closing-tags
@@ -310,7 +311,7 @@
     (let ((escaped (hash-ref %escape-chars c)))
       (if escaped
           (format port "&~a;" escaped)
-          (display c port))))
+          (put-char port c))))
   (string-for-each escape s))
 
 (define (object->escaped-html obj port)
@@ -329,7 +330,7 @@
   "Write ATTR and VALUE to PORT."
   (format port "~a=\"" attr)
   (attribute-value->html value port)
-  (display #\" port))
+  (put-char port #\"))
 
 (define (element->html tag attrs body port)
   "Write the HTML TAG to PORT, where TAG has the attributes in the
@@ -337,13 +338,13 @@ list ATTRS and the child nodes in BODY."
   (format port "<~a" tag)
   (for-each (match-lambda
              ((attr value)
-              (display #\space port)
+              (put-char port #\space)
               (attribute->html attr value port)))
             attrs)
   (if (and (null? body) (self-closing-tag? tag))
-      (display " />" port)
+      (put-string port " />")
       (begin
-        (display #\> port)
+        (put-char port #\>)
         (for-each (cut sxml->html <> port) body)
         (format port "</~a>" tag))))
 
@@ -358,7 +359,7 @@ list ATTRS and the child nodes in BODY."
      (doctype->html type port))
     ;; Unescaped, raw HTML output
     (('raw html)
-     (display html port))
+     (put-string port html))
     (('*ENTITY* name)
      (simple-format port "&~A;" name))
     (((? symbol? tag) ('@ attrs ...) body ...)