Updated MipsInstPrinter to print absolute hex offsets for branch instructions.
It is necessary to make the llvm-objdump output close to the gnu objdump output.
This implementation is based on the implementation for RISC-V.
OS Laboratory. Huawei Russian Research Institute. Saint-Petersburg
Add braces if then branch uses braces. https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements