[committed] store sp in alpha_push_dummy_call

[Andrew Cagney]

> Apparently, push_dummy_call is expected to update the sp:
> 
>   /* NOTE: cagney/2003-03-23: Disable this code when there is a
>      push_dummy_call() method.  Since that method will have already
>      stored the stack pointer (as part of creating the fake call
>      frame), and none of the code following that code adjusts the
>      stack-pointer value, the below call is entirely redundant.  */
>   if (DEPRECATED_DUMMY_WRITE_SP_P ())
>     DEPRECATED_DUMMY_WRITE_SP (sp);

THe comment is out-of-date - the check was removed but the comment not 
updated.  MIPS still supplies write_sp and hence writes the SP that way :-(

> Andrew, you have the same problem in your mips push_dummy_call
> routines, from which I was pattern matching.

The d10v is a safer bet.

Andrew