has_help_option() uses its own parser. It's inconsistent with
qemu_opts_parse(), as demonstrated by test-qemu-opts case
/qemu-opts/has_help_option. Fix by reusing the common parser.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200415074927.19897-5-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>