Remove inner folders of react/renderer/core

Summary:
This diff removes the inner folder of react/renderer/core, moving all its files into react/renderer/core

This is necessary to simplify the compilation of Fabric in OSS

More details: https://fb.quip.com/amaRA631DX3K

changelog: [internal] Internal

Reviewed By: fkgozali, JoshuaGross

Differential Revision: D22875854

fbshipit-source-id: e2d969c3ec67eab1bbdc9288e5a4285c740fa944

ReactCommon/react/renderer/core/BUCK

@@ -29,12 +29,6 @@ rn_xplat_cxx_library(
     exported_headers = subdir_glob(
         [
             ("", "*.h"),
-            ("events", "*.h"),
-            ("primitives", "*.h"),
-            ("componentdescriptor", "*.h"),
-            ("layout", "*.h"),
-            ("shadownode", "*.h"),
-            ("state", "*.h"),
         ],
         prefix = "react/renderer/core",
     ),