[MERGE #6109 @LouisLaf] Fix crawler assert of 2 lifetimes with same bytecode reg

Merge pull request #6109 from LouisLaf:arg_bug

The optimization copy-proping away argument object references in inlinees was missing a isJitOptimizeReg flag.
VSO bug: 20813519

Author: LouisLaf

lib/Backend/BackwardPass.cpp

@@ -4066,6 +4066,7 @@ BackwardPass::DeadStoreOrChangeInstrForScopeObjRemoval(IR::Instr ** pInstrPrev)
                         Assert(currFunc->HasStackSymForFormal(value));
                         StackSym * paramStackSym = currFunc->GetStackSymForFormal(value);
                         IR::RegOpnd * srcOpnd = IR::RegOpnd::New(paramStackSym, TyVar, currFunc);
+                        srcOpnd->SetIsJITOptimizedReg(true);
                         instr->ReplaceSrc1(srcOpnd);
                         this->ProcessSymUse(paramStackSym, true, true);