Fix *at syscalls flags decoding

Several *at decoders were defining own incomplete *atflags xlat
structures.  That was error prone, and fchownat decoder actually
failed to recognize AT_EMPTY_PATH.  Merging these incomplete
structures into the single at_flags xlat structure will fix
flags handling in all these decoders altogether.

* file.c: Define all AT_* constants used by *at decoders.
(at_flags): New xlat structure, with records for all AT_* constants.
(fstatatflags, linkat_flags, unlinkatflags): Remove.
(sys_newfstatat, sys_linkat, sys_unlinkat, sys_fchownat,
sys_utimensat):  Use at_flags.
1 file changed