[patch] Add start of mips32/mips64 support to sim/mips/mips.igen

[Andrew Cagney]

[Ah, summer and holidays...]

Chris,  could you please add yourself and my self to sim/MAINTAINERS as
mips sim maintainers.  I'll next go through each of the patches (but
they should be ok).  Once the backlog is cleared, we can probably start
using a much simpler self-approval process.

	Andrew