[llvm-libc] Fix missing virtual destructor

Summary: This patch adds a virtual destructor to the Command class.

Reviewers: sivachandra

Subscribers: mgorny, MaskRay, libc-commits

Tags: #libc-project

Differential Revision: https://reviews.llvm.org/D72253

libc/utils/HdrGen/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_tablegen(libc-hdrgen llvm-libc
   Command.h
+  Command.cpp
   Generator.cpp
   Generator.h
   IncludeFileCommand.cpp

libc/utils/HdrGen/Command.cpp

@@ -0,0 +1,15 @@
+//===-------- Base class for header generation commands ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Command.h"
+
+namespace llvm_libc {
+
+Command::~Command() {}
+
+} // namespace llvm_libc

libc/utils/HdrGen/Command.h

@@ -42,6 +42,8 @@ public:
     }
   };
 
+  virtual ~Command();
+
   virtual void run(llvm::raw_ostream &OS, const ArgVector &Args,
                    llvm::StringRef StdHeader, llvm::RecordKeeper &Records,
                    const ErrorReporter &Reporter) const = 0;