add support for protocol driver create_options

This patch enables protocol drivers to use their create options which
are not supported by the format.  For example, protcol drivers can use
a backing_file option with raw format.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qemu-option.h b/qemu-option.h
index 58136f3..4823219 100644
--- a/qemu-option.h
+++ b/qemu-option.h
@@ -70,6 +70,8 @@
     const char *value);
 int set_option_parameter_int(QEMUOptionParameter *list, const char *name,
     uint64_t value);
+QEMUOptionParameter *append_option_parameters(QEMUOptionParameter *dest,
+    QEMUOptionParameter *list);
 QEMUOptionParameter *parse_option_parameters(const char *param,
     QEMUOptionParameter *list, QEMUOptionParameter *dest);
 void free_option_parameters(QEMUOptionParameter *list);