Silence compiler warning about unused variable introduced in r343018

Since the body of the "else if" contains
 // TODO
I suppose someone will need the variable again at some point, but with
-Werror the warning made it not compile at all.

llvm-svn: 343071

llvm/lib/CodeGen/MachineFunction.cpp

@@ -657,7 +657,7 @@ MCSymbol *MachineFunction::addLandingPad(MachineBasicBlock *LandingPad) {
       }
     }
 
-  } else if (const auto *CPI = dyn_cast<CatchPadInst>(FirstI)) {
+  } else if (isa<CatchPadInst>(FirstI)) {
     // TODO
 
   } else {