qapi/string-output-visitor: fix bugs

in human mode, we are creating the string:

16-31 (16-31)

instead of

16-17 (10-1f)

because we forgot to pass 'true' as the human parameter on one of the
two calls to format_string.
Also, this is a worsening of quality; previously we would produce

16 (0x10)

to make it obvious which number was hex.
Fix these issues.
Reported-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

qapi/string-output-visitor.c

@@ -98,7 +98,7 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
 {
     if (r->end - r->begin > 1) {
         if (human) {
-            g_string_append_printf(sov->string, "%" PRIx64 "-%" PRIx64,
+            g_string_append_printf(sov->string, "0x%" PRIx64 "-%" PRIx64,
                                    r->begin, r->end - 1);
 
         } else {
@@ -107,7 +107,7 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
         }
     } else {
         if (human) {
-            g_string_append_printf(sov->string, "%" PRIx64, r->begin);
+            g_string_append_printf(sov->string, "0x%" PRIx64, r->begin);
         } else {
             g_string_append_printf(sov->string, "%" PRId64, r->begin);
         }
@@ -186,7 +186,7 @@ static void print_type_int(Visitor *v, int64_t *obj, const char *name,
         g_string_append(sov->string, " (");
         while (l) {
             Range *r = l->data;
-            format_string(sov, r, l->next != NULL, false);
+            format_string(sov, r, l->next != NULL, true);
             l = l->next;
         }
         g_string_append(sov->string, ")");