add new F_OFD_* macros to fcntl.h (open file description locks)

open file description locks are inherited across fork and only auto
dropped after the last fd of the file description is closed, they can be
used to synchronize between threads that open separate file descriptions
for the same file.

new in linux 3.15 commit 0d3f7a2dd2f5cf9642982515e020c1aee2cf7af6

include/fcntl.h

@@ -46,6 +46,10 @@ int posix_fallocate(int, off_t, off_t);
 #define O_WRONLY  01
 #define O_RDWR    02
 
+#define F_OFD_GETLK 36
+#define F_OFD_SETLK 37
+#define F_OFD_SETLKW 38
+
 #define F_DUPFD_CLOEXEC 1030
 
 #define F_RDLCK 0