Some secondary asm T3,T4,T5 functions

[David Miller]

I started playing with these, and one problem is that the
addxc/addxccc instructions do not accept an immediate field.  They
only accept rs1, rs2, rd arguments.  Please update your compat macros
to catch this.

This restriction exists because the instructions are encoded in the
IMPDEP{1,2} opcode area, like the rest of the VIS3 stuff, and an "I"
immediate field was therefore not available without using another
opcode in the opf space.

With this corrected I tried dive_1.asm and several tests fail, I'll
try to figure out why.