[patch] support syscall.sigaltstack for all archs

[Lai Jiangshan]

I have tested it on i686(Fedora7) and ia64(rhel5). It's ok
on these two hosts! I will commit it. 

Frank Ch. Eigler wrote:
> Lai Jiangshan <laijs@cn.fujitsu.com> writes:
> 
>> [...]order to offer probe for all archs, I added
>> syscall.sigaltstack(by probe kernel function do_sigaltstack) in
>> syscalls2.stp and deleted syscall.sigaltstack in i686/syscalls.stp,
>> ppc64/syscalls.stp and x86_64/syscalls.stp.
> 
> This makes good sense.  If you can find/create a testsuite item that
> checks this on a few hosts, please feel free to commit.
> 
> - FChE
> 
> 
>