Support moving support files instead of copy

[Eric]

Summary

Split from https://reviews.llvm.org/D100299

[jankratochvil]

LGTM

lldb/include/lldb/Symbol/CompileUnit.h

public:
   /// hands ownership of the line table to this object. The compile unit owns
   /// the line table object and will delete the object when it is deleted.
   ///
   /// \param[in] line_table
   ///     A line table object pointer that this object now owns.
   void SetLineTable(LineTable *line_table);
 
   void SetSupportFiles(const FileSpecList &support_files);
+  void SetSupportFiles(FileSpecList &&support_files);
 
   void SetDebugMacros(const DebugMacrosSP &debug_macros);
 
   /// Set accessor for the variable list.
   ///
   /// Called by the SymbolFile plug-ins after they have parsed the variable
   /// lists and are ready to hand ownership of the list over to this object.
   ///

lldb/source/Symbol/CompileUnit.cpp

else
     m_flags.Set(flagsParsedLineTable);
   m_line_table_up.reset(line_table);
 }
 
 void CompileUnit::SetSupportFiles(const FileSpecList &support_files) {
   m_support_files = support_files;
 }
 
+void CompileUnit::SetSupportFiles(FileSpecList &&support_files) {
+  m_support_files = std::move(support_files);
+}
+
 DebugMacros *CompileUnit::GetDebugMacros() {
   if (m_debug_macros_sp.get() == nullptr) {
     if (m_flags.IsClear(flagsParsedDebugMacros)) {
       m_flags.Set(flagsParsedDebugMacros);
       if (SymbolFile *symfile = GetModule()->GetSymbolFile())
         symfile->ParseDebugMacros(*this);
     }
   }