Add a virtual destructor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117280 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMAsmPrinter.cpp b/lib/Target/ARM/ARMAsmPrinter.cpp
index 7790484..61445c3 100644
--- a/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -75,6 +75,7 @@
     virtual void MaybeSwitchVendor(StringRef Vendor) = 0;
     virtual void EmitAttribute(unsigned Attribute, unsigned Value) = 0;
     virtual void Finish() = 0;
+    virtual ~AttributeEmitter() {}
   };
 
   class AsmAttributeEmitter : public AttributeEmitter {