[RFC][PATCH 1/2] fcntl.h: add new definitions for file-private lock cmd values

[Roland McGrath]

> My plan is to eventually submit this to become part of the POSIX
> standard though they won't take it until there's at least one shipping
> implementation. I assume that we just need to stick that inside of
> __USE_GNU for now, and if POSIX eventually picks it up then we'll just
> remove that protection?

Change it as appropriate, yes.

> Why does glibc have its own definitions for the fcntl F_* cmd values
> instead of using the ones in the uapi kernel headers? Would it not be
> simpler to just have the fcntl.h include those instead of duplicating
> them?

libc headers respect ISO C and POSIX name space constraints.
Kernel headers (even uapi ones) fail to.