Fix a small memory leak in VectorType.cpp and BlockPointer.cpp

[jasonmolenda]

Summary

Looking over the clang static analyzer, came across this old memory leak - looks like it's been around for at least four years. These two methods both call a formatters::*SyntheticFrontEndCreator method which new's an object and returns a pointer to it; they save save that pointer but never call delete. This patch puts it in an auto_ptr so it'll be destroyed when it goes out of scope.

[jasonmolenda]

Made the change in Xcode and the indentation was off.

[davide]

This is correct to the best of my understanding. Thank you Jason.

[tschuett]

auto_ptr is deprecated since C++11 and will be removed in C++17.

[davide]

In D85396#2198668, @tschuett wrote:

auto_ptr is deprecated since C++11 and will be removed in C++17.

@jasonmolenda you might want to use std::unique_ptr instead -- probably LLVM won't migrate to 17 for a while, but still.

[tschuett]

And you can write it as

std::unique_ptr<SyntheticChildrenFrontEnd> synthetic_children = std::make_unique(...);

[jasonmolenda]

Update to std::unique_ptr -- thanks for the reminder!

lldb/source/DataFormatters/VectorType.cpp

   size_t m_num_children;
 };
 
 } // namespace formatters
 } // namespace lldb_private
 
 bool lldb_private::formatters::VectorTypeSummaryProvider(
     ValueObject &valobj, Stream &s, const TypeSummaryOptions &) {
-  auto synthetic_children =
-      VectorTypeSyntheticFrontEndCreator(nullptr, valobj.GetSP());
-  if (!synthetic_children)
+  std::unique_ptr<SyntheticChildrenFrontEnd> synthetic_children;
+  synthetic_children.reset(
+      VectorTypeSyntheticFrontEndCreator(nullptr, valobj.GetSP()));
+  if (!synthetic_children.get())
     return false;
 
   synthetic_children->Update();
 
   s.PutChar('(');
   bool first = true;
 
   size_t idx = 0, len = synthetic_children->CalculateNumChildren();

lldb/source/Plugins/Language/CPlusPlus/BlockPointer.cpp

   CompilerType m_block_struct_type;
 };
 
 } // namespace formatters
 } // namespace lldb_private
 
 bool lldb_private::formatters::BlockPointerSummaryProvider(
     ValueObject &valobj, Stream &s, const TypeSummaryOptions &) {
-  lldb_private::SyntheticChildrenFrontEnd *synthetic_children =
-      BlockPointerSyntheticFrontEndCreator(nullptr, valobj.GetSP());
-  if (!synthetic_children) {
+  std::unique_ptr<SyntheticChildrenFrontEnd> synthetic_children;
+  synthetic_children.reset(
+      BlockPointerSyntheticFrontEndCreator(nullptr, valobj.GetSP()));
+  if (!synthetic_children.get()) {
     return false;
   }
 
   synthetic_children->Update();
 
   static const ConstString s_FuncPtr_name("__FuncPtr");
 
   lldb::ValueObjectSP child_sp = synthetic_children->GetChildAtIndex(