target/nios2: Add DisasContextBase to DisasContext

Migrate the is_jmp, tb and singlestep_enabled fields from
DisasContext into the base.  Use pc_first instead of tb->pc.
Increment pc_next prior to decode, leaving the address of
the current insn in dc->pc.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
1 file changed