libsepol: Add two new Xen initial SIDs

Xen uses the initial SIDs domU and domDM in its toolstack, so it makes
sense to add these to xen_sid_to_str[] in kernel_to_common.h

Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>

libsepol/src/kernel_to_common.h

@@ -57,6 +57,8 @@ static const char * const xen_sid_to_str[] = {
 	"iomem",
 	"irq",
 	"device",
+	"domU",
+	"domDM",
 };
 
 #define XEN_SID_SZ (sizeof(xen_sid_to_str)/sizeof(xen_sid_to_str[0]))