Recent Linux uapi <linux/xattr.h> headers define XATTR_NAME_SMACK.
The <sys/xattr.h> include at the top of lib/lsm.h means that even
though the direct include of <linux/xattr.h> is guarded, it may
have already happened transitively anyway.
(The alternative fixes would be to hard-code the correct value for
XATTR_NAME_SMACK here instead, or #undef XATTR_NAME_SMACK.)
Doing a world writeable mkdir and _then_ adding a label seems like a race
window, so set the global "create stuff with these labels" context, then
do the creates.
portability.h to new lib/lsm.h. Update ls.c to use it.
Fix "ls . toys" (two directories when one is . or ..), which was filtering
out the . as something we shouldn't recurse into even though it was explicitly
listed on the command line. For some reason "ls -Z . toys" is still segfaulting
though (but "ls -Z ." isn't), need to figure out why...
