Make EHFrames available to sub-classes of RTDyldMemoryManager.

[marsupial]

Summary

This information can be useful; and in the case of Win64, necessary for getting exceptions to work in the JIT.

[marsupial]

Ping.
@lhames Is there any chance to get this in before 5.0...it removes the need to store this same exact information 2x in our code base.

[lhames]

LGTM - Go for it!

include/llvm/ExecutionEngine/RTDyldMemoryManager.h

public:
   /// found, this function returns a null pointer. Otherwise, it prints a
   /// message to stderr and aborts.
   ///
   /// This function is deprecated for memory managers to be used with
   /// MCJIT or RuntimeDyld.  Use getSymbolAddress instead.
   virtual void *getPointerToNamedFunction(const std::string &Name,
                                           bool AbortOnFailure = true);
 
-private:
+protected:
   struct EHFrame {
     uint8_t *Addr;
     size_t Size;
   };
-  std::vector<EHFrame> EHFrames;
+  typedef std::vector<EHFrame> EHFrameInfos;
+  EHFrameInfos EHFrames;
 };
 
 // Create wrappers for C Binding types (see CBindingWrapping.h).
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(
     RTDyldMemoryManager, LLVMMCJITMemoryManagerRef)
 
 } // end namespace llvm
 
 #endif // LLVM_EXECUTIONENGINE_RTDYLDMEMORYMANAGER_H