[mips][microMIPS] Extending size reduction pass with ADDIUSP and ADDIUR1SP

Author: milena.vujosevic.janicic
Reviewers: sdardis
The patch extends size reduction pass for MicroMIPS.
The following instructions are examined and transformed, if possible:
ADDIU instruction is transformed into 16-bit instruction ADDIUSP
ADDIU instruction is transformed into 16-bit instruction ADDIUR1SP
Function InRange is changed to avoid left shifting of negative values, since 
that caused some sanitizer tests to fail (so the previous patch 
Differential Revision: https://reviews.llvm.org/D34511

llvm-svn: 308011