[mips] Define an overloaded version of function MipsInstrInfo::AnalyzeBranchAdd.

This function will be used later when the capability to search delay slot
filling instructions in successor blocks is added. No intended functionality
changes.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176325 91177308-0d34-0410-b5e6-96231b3b80d8