adding movz to machine description

[Petar Bajic]

> It may be correct for the pattern to not be matched with expand.  It's
> OK if the if-conversion pass picks it up, which seems to be what is
> happening for you.
>
> If the generated code you are getting is wrong, then problem is likely
> in the define_insn patterns somewhere.  They don't correct represent
> what the instruction does, or they don't correctly implement it.
>
> Ian

After some modifications, I managed to make gcc use my define_expand - I see 
it in debug.11.ce1 and following files, but then it disapears in 
debug.17.combine, and in the end it does not appear in asm code. How to find 
out what kills it? :)