Revert "Copy files for rapidjson build"

This reverts commit a5e9ba0cb035d35c26c6741071888e5b501601d0.

I don't think we should copy these headers to the out directory.  Instead, we should create BUILD.gn files for tink (and/or modify the tink source) to work within the Fuchsia Build System.

Change-Id: I88349890ce15ea48b46c6a4a5df769b4e5c9c4a0