ls: fix crash on systems with SELinux but without xattr support

ls: fix crash on systems with SELinux but without xattr support

This was seen on termux on Android with ./configure --disable-xattr
where listxattr() and getxattr() returned ENOTSUP.
Then the valid security context obtained by file_has_aclinfo()
was discounted, and problematically then freed multiple times.
Reported at https://github.com/termux/termux-packages/issues/23752

* src/ls.c (file_has_aclinfo_cache): Only discount the returned
acl info when all components are defaulted due to being unsupported.