api: Add support for SCMP_ACT_KILL_PROCESS

api: Add support for SCMP_ACT_KILL_PROCESS

This patch adds support for killing the entire process via
the SCMP_ACT_KILL_PROCESS action.  To maintain backward
compatibility, SCMP_ACT_KILL defaults to SCMP_ACT_KILL_THREAD.
Support for KILL_PROCESS was added into the Linux kernel in
v4.14.

This addresses GitHub Issue #96 - RFE: add support for
SECCOMP_RET_KILL_PROCESS

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
[PM: minor comment tweak in seccomp.h.in]
Signed-off-by: Paul Moore <paul@paul-moore.com>