Make DWARFExpression::GetLocationExpression public

[Eric]

Summary

This method is used to get the DataExtractor when the expression is a location list.

[Eric]

Context for this: I am working on an lldb-based debugging tool that needs to be able to generate code to evaluate a dwarf expression without evaluating it. I need access to this method to be able to handle location lists.

[labath]

If you start to need to make more changes for your project, we'll need to have a bigger discussion, but right now, this seems ok.

lldb/include/lldb/Expression/DWARFExpression.h

public:
   }
 
   bool DumpLocationForAddress(Stream *s, lldb::DescriptionLevel level,
                               lldb::addr_t func_load_addr, lldb::addr_t address,
                               ABI *abi);
 
   bool MatchesOperand(StackFrame &frame, const Instruction::Operand &op);
 
+  llvm::Optional<DataExtractor>
+  GetLocationExpression(lldb::addr_t load_function_start,
+                        lldb::addr_t addr) const;
+
 private:
   /// Pretty-prints the location expression to a stream
   ///
   /// \param[in] s
   ///     The stream to use for pretty-printing.
   ///
   /// \param[in] data
   ///     The data extractor.
   ///
   /// \param[in] level
   ///     The level of detail to use in pretty-printing.
   ///
   /// \param[in] abi
   ///     An optional ABI plug-in that can be used to resolve register
   ///     names.
   void DumpLocation(Stream *s, const DataExtractor &data,
                     lldb::DescriptionLevel level, ABI *abi) const;
 
-  llvm::Optional<DataExtractor>
-  GetLocationExpression(lldb::addr_t load_function_start,
-                        lldb::addr_t addr) const;
-
   /// Module which defined this expression.
   lldb::ModuleWP m_module_wp;
 
   /// A data extractor capable of reading opcode bytes
   DataExtractor m_data;
 
   /// The DWARF compile unit this expression belongs to. It is used to evaluate
   /// values indexing into the .debug_addr section (e.g. DW_OP_GNU_addr_index,