poll.2: The negate-fd-to-ignore technique does not work for file descriptor 0

See https://bugzilla.kernel.org/show_bug.cgi?id=79411

Reported-by: Nadav Har'El <nyh@math.technion.ac.il>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
fcntl.2: Use proper page cross-references in F_NOTIFY discussion

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
syscalls.2: grfix

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
set_tid_address.2: Use "thread" rather than "process" in DESCRIPTION

Reported-by: Rich Felker <dalias@libc.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
set_tid_address.2: SEE ALSO: add gettid(2)

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>