RFA/dwarf: Fix the GCC 2.95.3 store.exp regression for multi-register variables

[Stephane Carrez]

Hi Daniel,

Daniel Jacobowitz wrote:
> This kills both a hack and the regression discussed on gdb@.  Instead of
> returning the value of the register and the register number, if the
> expression evaluator only returns the register number, we can use
> value_from_register.  This way we share multi-register variable handling
> with the non-LOC_COMPUTED case.
> 
> This patch removes a FIXME and an interface I didn't much like (the lval
> argument to dwarf_expr_read_reg) so I'm pretty happy with it.  Everything
> should go back to working that worked before.
> 
Great!

FYI, it fixes the problem on m6811-elf (PR 1107).

Thanks,
	Stephane