[MERGE #4256 @MikeHolman] fix missing implicit kill for DIV

Merge pull request #4256 from MikeHolman:implicitkills

RDX:RAX are always modified by DIV, so we need to mark the implicit kill in peeps. We were already doing this for x86, but case for DIV was missing on x64.

OS: 14520690

lib/Backend/amd64/PeepsMD.cpp

@@ -29,7 +29,7 @@ PeepsMD::ProcessImplicitRegs(IR::Instr *instr)
     {
         this->peeps->ClearReg(RegRDX);
     }
-    else if (instr->m_opcode == Js::OpCode::IDIV)
+    else if (instr->m_opcode == Js::OpCode::IDIV || instr->m_opcode == Js::OpCode::DIV)
     {
         if (instr->GetDst()->AsRegOpnd()->GetReg() == RegRDX)
         {