sys/inotify.h: add IN_MASK_CREATE from linux v4.19

inotify_add_watch flag to prevent modifying existing watch descriptors,
when used on an already watched inode it fails with EEXIST.
added in linux commit 4d97f7d53da7dc830dbf416a3d2a6778d267ae68

include/sys/inotify.h

@@ -40,6 +40,7 @@ struct inotify_event {
 #define IN_ONLYDIR       0x01000000
 #define IN_DONT_FOLLOW   0x02000000
 #define IN_EXCL_UNLINK   0x04000000
+#define IN_MASK_CREATE   0x10000000
 #define IN_MASK_ADD      0x20000000
 
 #define IN_ISDIR         0x40000000