[PATCH] MIPS gas: Fix macro expansions for .set noat

[Maciej W. Rozycki]

Thiemo,

 More comments about that change -- as I understand our policy wrt $at 
being used with ".set noat" in effect is to go for it regardless and only 
issue a warning (that can be converted to an error with --fatal-warnings).  
Therefore we shouldn't use as_bad() in this case.  Moreover, the situation 
is actually already handled in general -- see the bottom exit point from 
macro() -- so we should really only track down the failing execution path 
within that function and check whether its epilogue correctly executes a 
functional equivalent of this code:

if (used_at)
	break;
else
	return;

  Maciej