RFC: .sleb128 and bignums

[Alan Modra]

Note that there are other inconsistencies with gas expression
evaluation.  For instance

	    case O_right_shift:
	      /* We always use unsigned shifts, to avoid relying on
		 characteristics of the compiler used to compile gas.  */

while other operators use signed evaluation.  This is without even
considering what happens with bignums.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre