alpha haifa regression

[Jeffrey A Law]

  In message < 199710072012.VAA15311@phal.cygnus.co.uk >you write:
  > I just checked it for alpha. pa and sh.  For a TYPE argument, va_arg
  > basically casts (or assigns) a void* to a TYPE*, and then dereferences
  > the TYPE*.  The result is a memory access that has MEM_IN_STRUCT_P set
  > iff TYPE is a struct.
  > 
  > I propose to cast to a (struct { TYPE t;} *) instead, and dereference that
  > and select the t member (can of course both be done with the -> operator).
I think this is more complicated than we need.

Emitting the blockage is easy and is unlikely to have any noticable impact
on performance.

jeff