[patch] change to MIPS 4650 instruction support

[Eric Christopher]

Daniel Jacobowitz wrote:
> 
> I envision the CPU argument setting defaults for a collection of
> extension flags for all sorts of groups of instructions (like single
> float, double float, mad, etc.) as well as a scheduling or otherwise
> quirky policy, and then allowing the instruction flags to be
> overridden.
> 

Do you mean within the assembler or the compiler?  I"m definitely
thinking of something similar for the compiler (look at the arm port for
examples), and am working on the infrastructure changes necessary to
support this.

-eric