v2 of seccomp filter c/r patches

[Tycho Andersen <tycho.andersen@canonical.com>]

Hi all,

Here is v2 of the seccomp filter c/r set. The patch notes have individual
changes from the last series, but there are two points not noted:

* The series still does not allow us to correctly restore state for programs
  that will use SECCOMP_FILTER_FLAG_TSYNC in the future. Given that we want to
  keep seccomp_filter's identity, I think something along the lines of another
  seccomp command like SECCOMP_INHERIT_PARENT is needed (although I'm not sure
  if this can even be done yet). In addition, we'll need a kcmp command for
  figuring out if filters are the same, although this too needs to compare
  seccomp_filter objects, so it's a little screwy. Any thoughts on how to do
  this nicely are welcome.

* I've dropped the bpf converter bug from the set and will submit it
  separately.

Alexei mentioned that this should go via net-next to minimize cross-tree
conflicts. Does that make sense here?

Thanks,

Tycho