unistd: fix typo This typo ended up incompatibly re-defining the macro link() during -DGNULIB_POSIXCHECK=1. However, gcc's pragma system_header squelches that particular warning, so this typo went unnoticed. * lib/unistd.in.h (linkat) [GNULIB_POSIXCHECK]: Fix typo. Signed-off-by: Eric Blake <ebb9@byu.net>