addi/daddi are deprecated by MIPS for years, and MIPS r6 remove
them.
They should be replace with addiu:
ADDIU performs the same arithmetic operation but
does not trap on overflow.
Reviewed-by: Shiyou Yin <yinshiyou-hf@loongson.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>