virJSONValue: remove unused 'protect' property

The last usage was removed by commit <167028e3>
Signed-off-by: NJán Tomko <jtomko@redhat.com>

src/util/virjson.c

@@ -78,7 +78,6 @@ struct _virJSONArray {
 
 struct _virJSONValue {
     int type; /* enum virJSONType */
-    bool protect; /* prevents deletion when embedded in another object */
 
     union {
         virJSONObject object;
@@ -395,7 +394,7 @@ void
 virJSONValueFree(virJSONValuePtr value)
 {
     size_t i;
-    if (!value || value->protect)
+    if (!value)
         return;
 
     switch ((virJSONType) value->type) {