Hello,

This patch implements a 4-bit PPC ELF specific push_dummy_call method. 
It then adds a work-around (*_broken_push_dummy_call) for what would 
appear to be GCC bugs.  This fixes ~200 failures (give or take the 3 
fixed by the workaround).

Ok to commit?

Andrew

PS: The apparent bugs are:

- small odd structs get passed in memory instead of a register (ref 
structs.exp:Fun3).
- small even structs get passed right, instead of left, aligned in the 
register (ref structs.exp:Fun[12]).

PS: Backtraces are a bit sick.

PPS: Oh, note the "hack" to find the TOC from the function's entry point 
address.  Without it malloc() fails.