[MLIR] Fix release build: reference to NDEBUG guarded function (NFC)

With LDBG(), the code isn't guarded in release mode, even if the optimizer
will remove it because there is a `if (false)` statement. We need the
function declaration to be there at minima.

Author: joker-eph

mlir/lib/Transforms/Utils/Inliner.cpp

@@ -348,13 +348,11 @@ static void collectCallOps(iterator_range<Region::iterator> blocks,
 // InlinerInterfaceImpl
 //===----------------------------------------------------------------------===//
 
-#ifndef NDEBUG
 static std::string getNodeName(CallOpInterface op) {
   if (llvm::dyn_cast_if_present<SymbolRefAttr>(op.getCallableForCallee()))
     return debugString(op);
   return "_unnamed_callee_";
 }
-#endif
 
 /// Return true if the specified `inlineHistoryID`  indicates an inline history
 /// that already includes `node`.