options/posix: define MADV_{NORMAL,RANDOM,FREE}
#define MREMAP_MAYMOVE 1
#define MREMAP_FIXED 2
+#define MADV_NORMAL 0
+#define MADV_RANDOM 1
#define MADV_SEQUENTIAL 2
#define MADV_WILLNEED 3
#define MADV_DONTNEED 4
+#define MADV_FREE 5
// Missing: posix_typed_mem_open(), POSIX_TYPED constants and related stuff.
