c/r of pdeath

[Serge E. Hallyn]

Hi Oren,

commit 9a45e26c0aabda6a94e2ac620befd8ee12a7363d adds
reset of pdeath_signal.  It does so unconditionally.  I
don't think that's safe.  Perhaps if pdeath_signal is
anything other than 0, it should only be restored if
the task is capable(CAP_KILL)?

-serge