signals: Calculate peek offset in-place

No need in extra variable for that.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
signals: Move nr variable into peeking loop

And sanitize its usage a little bit.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
signals: Don't forget to allocate SiginfoEntry

The se variable is just an array of pointers on these
objects. Need to allocate the objects themselves.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
signals: Don't collect siginfo_t-s on stack

We've moved signinfos on core entry, thus the bits with
siginfo-s themselves cannot sit on stack any longer.
Otherwise we would overwritem them with next batch and
will feed stack pointer to the caller, thus causing a
data and garbage on the stack to be written into image
instead of siginfo data.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
signals: Sanitize j loop control variable

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
signals: Comments and while (1) loop

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>