[m-dev.] for review: new debugger command set (part 1 of 4)

[Zoltan Somogyi]

> > Index: trace/mercury_trace_internal.h
> ...
> > +#undef	USE_GCC_GLOBAL_REGISTERS
> 
> I don't think that is a good idea.  Doing this is at best fragile. 
> Doing this in a header file is extrememly dangerous.

That line was there just to avoid a gcc abort while I was looking for other
problems; it was not meant to be permanent.

Removing it however means that assignments such as

	MR_spied_procs[2] = MR_spied_procs[1];

will cause gcc aborts. I added code to configure.in to check whether such
assignments cause gcc aborts. If yes, mercury_conf.h will now define the
macro MR_CANNOT_USE_STRUCTURE_ASSIGNMENT, and this will cause
mercury_array_macros.h to call MR_memcpy instead of executing
assingments like the one above.

Zoltan.