add PR_MPX_*_MANAGEMENT prctl options

new in linux v3.19, commit fe3d197f84319d3bce379a9c0dc17b1f48ad358c
used for on-demand kernel allocation of bounds tables for mpx on x86

include/sys/prctl.h

@@ -116,6 +116,9 @@ struct prctl_mm_map {
 #define PR_SET_THP_DISABLE      41
 #define PR_GET_THP_DISABLE      42
 
+#define PR_MPX_ENABLE_MANAGEMENT  43
+#define PR_MPX_DISABLE_MANAGEMENT 44
+
 int prctl (int, ...);
 
 #ifdef __cplusplus