MIPS64: Fix various code-patching sequnces to use the updated li().

This includes:
     Assembler::RelocateInternalReference()
     RelocInfo::IsPatchedReturnSequence()
     BreakLocationIterator::SetDebugBreakAtReturn()
     BreakLocationIterator::SetDebugBreakAtSlot()
     FullCodeGenerator::EmitReturnSequence()
     Assembler::CheckTrampolinePool()

This is speculative fix, as much of this is not testable yet.