acl: First step towards more consistent function names.
* lib/acl.h (xset_acl): New declaration.
(set_acl): Mark deprecated.
(xcopy_acl): New declaration.
(copy_acl): Mark deprecated.
* lib/set-acl.c (xset_acl): Renamed from set_acl.
(set_acl): New function.
* lib/copy-acl.c (xcopy_acl): Renamed from copy_acl.
(copy_acl): New function.
* tests/test-set-mode-acl.c (main): Test xset_acl instead of set_acl.
* tests/test-copy-acl.c (main): Test xcopy_acl instead of copy_acl.