Changes to location/align/... code

Hi,

just a note for those interested in pcc internals:

I have now cleaned up how the location counters/naming/... in pcc works.
I have tried to fix it for some of the targets also but not sure I got
everything correct.  ANyway, short description:

The following target-dependent routines will be called:

- defloc(struct symtab *sp);
        Responsible to set up segments, alignment, name etc.
        Will be called before initialized aggregates _and_ before each
        function is written out. If called with sp == NULL, then
	target should assume that everything is changed in a non-predictable
	way (like after asm() statements).

- ninval()/infld()/zbits()
        Same as now, may be called one or more times                            

Strings:
- instring(struct symtab *sp);
        or
- inwstring(struct symtab *sp);
        print out a string/wide string, stored in sname in sp.
	defloc() is _not_ called before, but may be called from this
	routine.

Uninitialized data:
- defzero(struct symtab *sp)    /* New function */
        Define the variable in bss or equivalent.
	defloc() is _not_ called before, but may be called from this
	routine.

-- Ragge