maint: prefer enums over macros for sources used for multiple programs

maint: prefer enums over macros for sources used for multiple programs

* src/chown.h (enum chown_modes): New type.
(CHOWN_CHOWN, CHOWN_CHGRP): Define as an enum instead of a macro.
* src/chown-chgrp.c (chown_mode): Use "enum chown_modes" instead of
"int".
* src/chown-chown.c (chown_mode): Likewise.
* src/ls.h (enum ls_modes): New type.
(LS_LS, LS_MULTI_COL, LS_LONG_FORMAT): Define as an enum instead of a
macro.
* src/ls-dir.c (ls_mode): Use "enum ls_modes" instead of "int".
* src/ls-ls.c (ls_mode): Likewise.
* src/ls-vdir.c (ls_mode): Likewise.
* src/uname.h (enum uname_modes): New type.
(UNAME_UNAME, UNAME_ARCH): Define as an enum instead of a macro.
* src/uname-arch.c (uname_mode): Use "enum uname_modes" instead of
"int".
* src/uname-uname.c (uname_mode): Likewise.