readelf: decode LA48 and ASG_DISABLE feature flags

MFC after:	1 week
Sponsored by:	The FreeBSD Foundation

contrib/elftoolchain/readelf/readelf.c

@@ -3680,6 +3680,8 @@ static struct flag_desc note_feature_ctl_flags[] = {
 	{ NT_FREEBSD_FCTL_PROTMAX_DISABLE,	"PROTMAX_DISABLE" },
 	{ NT_FREEBSD_FCTL_STKGAP_DISABLE,	"STKGAP_DISABLE" },
 	{ NT_FREEBSD_FCTL_WXNEEDED,		"WXNEEDED" },
+	{ NT_FREEBSD_FCTL_LA48,			"LA48" },
+	{ NT_FREEBSD_FCTL_ASG_DISABLE,		"ASG_DISABLE" },
 	{ 0, NULL }
 };