Mips assembler: Assembler macro ADDIU $rs,imm

This patch adds alias for addiu instruction which enables following syntax:

    addiu $rs,imm

The macro is translated as:

    addiu $rs,$rs,imm


Contributer: Vladimir Medic


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181729 91177308-0d34-0410-b5e6-96231b3b80d8