On the fsfs-format7 branch:  drop the copy-from cache previously attached
to each svn_fs_root_t object.  Creation and maintenance overhead by far
outweights the gains because most are now backed by the dag node cache.

* subversion/libsvn_fs_fs/transaction.h
  (svn_fs_fs__paths_changed): drop copyfrom_cache parameter

* subversion/libsvn_fs_fs/transaction.c
  (fold_change): remove code that filled the copyfrom_cache
  (process_changes,
   svn_fs_fs__txn_changes_fetch,
   svn_fs_fs__paths_changed): update callers

* subversion/libsvn_fs_fs/tree.c
  (fs_rev_root_data_t): drop copyfrom_cache;
                        link fsap_data directly to root_dir now
  (root_node,
   svn_fs_fs__node_id,
   fs_paths_changed,
   svn_fs_fs__verify_root): update
  (make_revision_root): simplify svn_fs_root_t creation
  (fs_copied_from): drop copyfrom_cache lookup

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1483374 13f79535-47bb-0310-9956-ffa450edef68