Add virtual destructor to WasmYAML::Section or avoid memory leak

[sbc100]

Summary

Tested locally with -DLLVM_USE_SANITIZER=Address

[dschuff]

include/llvm/ObjectYAML/WasmYAML.h

111

This probably should be out-of-line: http://llvm.org/docs/CodingStandards.html#provide-a-virtual-method-anchor-for-classes-in-headers

[sbc100]

• move virtual method to cpp file

include/llvm/ObjectYAML/WasmYAML.h

struct Signature {
   uint32_t Index;
   SignatureForm Form;
   std::vector<ValueType> ParamTypes;
   ValueType ReturnType;
 };
 
 struct Section {
   Section(SectionType SecType) : Type(SecType) {}
+  virtual ~Section() {}
 
   SectionType Type;
   std::vector<Relocation> Relocations;
 };
 
 struct CustomSection : Section {
   CustomSection() : Section(wasm::WASM_SEC_CUSTOM) {}
   static bool classof(const Section *S) {