Revert "[MC] Explicitly mark MCSymbol for MO_ExternalSymbol (llvm#108880)"

This reverts commit 3d0846b.

Author: Zentrik

llvm/lib/Target/X86/X86MCInstLower.cpp

@@ -348,12 +348,8 @@ MCOperand X86MCInstLower::LowerMachineOperand(const MachineInstr *MI,
     return MCOperand::createImm(MO.getImm());
   case MachineOperand::MO_MachineBasicBlock:
   case MachineOperand::MO_GlobalAddress:
+  case MachineOperand::MO_ExternalSymbol:
     return LowerSymbolOperand(MO, GetSymbolFromOperand(MO));
-  case MachineOperand::MO_ExternalSymbol: {
-    MCSymbol *Sym = GetSymbolFromOperand(MO);
-    Sym->setExternal(true);
-    return LowerSymbolOperand(MO, Sym);
-  }
   case MachineOperand::MO_MCSymbol:
     return LowerSymbolOperand(MO, MO.getMCSymbol());
   case MachineOperand::MO_JumpTableIndex: