sys/mman.h: add MADV_POPULATE_(READ|WRITE) from linux v5.14

Add madvise flags to populate(prefault) page tables
see
  linux commit 4ca9b3859dac14bbef0c27d00667bb5b10917adb
  mm/madvise: introduce MADV_POPULATE_(READ|WRITE) to prefault page tables

include/sys/mman.h

@@ -95,6 +95,8 @@ extern "C" {
 #define MADV_KEEPONFORK  19
 #define MADV_COLD        20
 #define MADV_PAGEOUT     21
+#define MADV_POPULATE_READ 22
+#define MADV_POPULATE_WRITE 23
 #define MADV_HWPOISON    100
 #define MADV_SOFT_OFFLINE 101
 #endif