vfs: restore platform specific POSIX sys_acl_set_file() functions

vfs: restore platform specific POSIX sys_acl_set_file() functions

92b149954237a445594c993b79a860c63113d54b removed SMB_VFS_SYS_ACL_SET_FILE() and
all the VFS module implementations. But sys_acl_set_file() in vfs_default calls
into sys_acl_set_file() in sysacls.c which calls back into platform specific
modules.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14619

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Björn Jacke <bjacke@samba.org>
Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Thu Jan 28 15:21:02 UTC 2021 on sn-devel-184