* LRU cache for caching graphs

* static

* LRU Cache

* Cache graph

* Make data members static

* Temp test case functional

* Temp test case functional

* Fix shape

* Make lru local to dynamic wrapper

* Make cache thread safe

* Remove static copies of data members

* Add a separator  between shapes of different inputs

* Clear list and map in destructor

* Caching on values of shape relevant inputs

* Replace cout's by NGRAPH_INFO

* Add a environment variable for cache size

* Add mutex header

* style

* change to int64_t

* Save the cloned function to get the output shape to allocate output storage

* Pass inputs without wrapping

* Fix conv shape relevant inputs

* gcc 4.8 doesnt support ostring stream as a copyable object

* Pass key by reference

* PR feedback

* Apply suggestions from code review

* Replace malloc
Co-authored-by: Scott Cyphers <diyessi@users.noreply.github.com>
Co-authored-by: Robert Kimball <robert.kimball@intel.com>