[WebAssembly] Add 'final' to some classes. NFC.

llvm-svn: 254073
diff --git a/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.h b/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.h
index 80fe29d..319c8ee 100644
--- a/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.h
+++ b/llvm/lib/Target/WebAssembly/InstPrinter/WebAssemblyInstPrinter.h
@@ -23,7 +23,7 @@
 class MCOperand;
 class MCSubtargetInfo;
 
-class WebAssemblyInstPrinter : public MCInstPrinter {
+class WebAssemblyInstPrinter final : public MCInstPrinter {
 public:
   WebAssemblyInstPrinter(const MCAsmInfo &MAI, const MCInstrInfo &MII,
                          const MCRegisterInfo &MRI);