[0/4] Nios II opcodes/assembler/disassembler update

[Sandra Loosemore <sandra at codesourcery dot com>]

Altera has been developing a revised version of the Nios II ISA which 
will include all of new instructions, new instruction formats, and 
re-encoding of existing instructions.  This will be treated as a variant 
of the Nios II architecture although code won't be link-compatible with 
the existing ISA.

This set of patches lays the groundwork for adding support for new nios2 
ISA variants in binutils and gdb by adopting more uniform conventions 
for manipulating instruction words, removing hard-wired instruction 
encodings and implicit assumptions about instruction formats, and 
refactoring code to improve abstraction and reduce problems with 
combinatorial explosion.  There's no new architecture support here yet, 
just a lot of code refactoring and interface changes.  We'd like to 
contribute this part now because (a) it is generally an improvement to 
the existing code and (b) minimizing divergence between our development 
branch and the FSF repository is a good thing too.

There are four parts to this patch series, but they'll all need to be 
committed together.  I can self-approve parts 1-3 and Yao (GDB port 
maintainer) has agreed that part 4 qualifies as obvious.  I'll check 
these in tomorrow, probably.

1: new opcodes macros and data structure changes.
2: disassembler changes
3: assembler rewrite
4: minimal GDB update to use new interfaces

-Sandra