[NFC] Fix uninitialized scalar variable found by Coverity static analyzer tool

[Manna]

Summary

Reported by Coverity Static Analyzer Tool:

Inside "MicrosoftDemangle.cpp" file, in llvm::​ms_demangle::​Demangler::​demangleTemplateInstantiationName(std::​basic_string_view<char, std::​char_traits<char>> &, llvm::​ms_demangle::​NameBackrefBehavior): Use of an uninitialized value OuterContext. Field OuterContext.FunctionParams is uninitialized when calling swap in the function.

[Manna]

I am looking into more details. Closing the PR

llvm/include/llvm/Demangle/MicrosoftDemangle.h

 
 private:
   AllocatorNode *Head = nullptr;
 };
 
 struct BackrefContext {
   static constexpr size_t Max = 10;
 
-  TypeNode *FunctionParams[Max];
+  TypeNode *FunctionParams[Max] = nullptr;
   size_t FunctionParamCount = 0;
 
   // The first 10 BackReferences in a mangled name can be back-referenced by
   // special name @[0-9]. This is a storage for the first 10 BackReferences.
   NamedIdentifierNode *Names[Max];
   size_t NamesCount = 0;
 };