RFE: Add support for SCMP_FLTATR_CTL_SSB

[KentaTada]

runc needs to use SCMP_FLTATR_CTL_SSB in opencontainers/runc#2430 to make bytecode interpreters including Ruby and Python faster when users can disable mitigation.

[KentaTada]

SCMP_FLTATR_CTL_SSB was not included in the release of libseccomp v2.4.3.
So, we need to wait for the next release of libseccomp at first.

[pcmoore]

Adding the pending/libseccomp label to indicate this is dependent on a new libseccomp release (v2.5.0).

[KentaTada]

@pcmoore
I'll try to implement this feature if this priority is low.

[pcmoore]

Thanks @KentaTada, help is always appreciated.

FWIW, now that core libseccomp v2.5.0 has been released @drakenclimber and I are going to try and spend some more time cleaning up the golang bindings.

[KentaTada]

@pcmoore Thanks!
I created #51

[KentaTada]

#51 has been already merged.