String constants could be used for string option values.

Thanks to Frederik Kriewitz for the patch.

conf/confbase.Y

@@ -77,6 +77,7 @@ CF_DECLS
 %type <time> datetime
 %type <a> ipa
 %type <px> prefix prefix_or_ipa
+%type <t> text
 %type <t> text_or_none
 
 %nonassoc PREFIX_DUMMY
@@ -191,6 +192,14 @@ datetime:
    }
  ;
 
+text:
+   TEXT
+ | SYM {
+     if ($1->class != (SYM_CONSTANT | T_STRING)) cf_error("String expected");
+     $$ = SYM_VAL($1).s;
+   }
+ ;
+
 text_or_none:
    TEXT { $$ = $1; }
  |      { $$ = NULL; }