alpha: fix sigaction decoding

Since the rt_sigaction syscall on alpha doesn't have a sa_restorer,
do not include it in the kernel struct.

* signal.c (struct new_sigaction): Disable sa_restorer on alpha.
hppa: fix sigaction decoding

Since the rt_sigaction syscall on hppa doesn't have a sa_restorer,
do not include it in the kernel struct.

We also have to undefine SA_RESTORER so that code doesn't try to
use it.  The headers will export this, but the syscall doesn't
actually respect it.

* signal.c (SA_RESTORER): Undefine when HPPA is defined.
(struct new_sigaction): Disable sa_restorer on hppa.
alpha/sparc: fix arg count for rt_sigaction

Both these arches have a rt_sigaction syscall that takes 5 args, not 4.

* linux/alpha/syscallent.h (rt_sigaction): Change nargs to 5.
* linux/sparc/syscallent.h (rt_sigaction): Change nargs to 5.
sigaction test: support arches w/out SA_RESTORER and swapped args

Running Linux 3.15 (sparc64) and glibc 2.17 (sparc32) triggers a
rt_sigaction call that does not use SA_RESTORER and has an order
where it inserts a restorer and a size.  The current tests don't
support that ordering, so add another regex.

* tests/sigaction.awk: Support no SA_RESTORER and swapped args.