On the fsfs-format7 branch:  Tweak the string table getter APIs to
also return the size of the string.  Update tests and callers.
Finally, drop an unused API

* subversion/libsvn_fs_fs/string_table.h
  (svn_fs_fs__string_table_copy_string): drop
  (svn_fs_fs__string_table_get,
   svn_fs_fs__string_table_get_func): add LENGTH out parameter

* subversion/libsvn_fs_fs/string_table.c
  (svn_fs_fs__string_table_copy_string): drop
  (svn_fs_fs__string_table_get,
   svn_fs_fs__string_table_get_func): update implementation

* subversion/libsvn_fs_fs/changes.c
  (svn_fs_fs__changes_get_list,
   svn_fs_fs__changes_get_list_func): update callers

* subversion/libsvn_fs_fs/noderevs.c
  (svn_fs_fs__noderevs_get,
   svn_fs_fs__noderevs_get_func): ditto

* subversion/tests/libsvn_fs_fs/string-table-test.c
  (create_empty_table_body,
   short_string_table_body, 
   large_string_table_body, 
   many_strings_table_body): update tests


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1483386 13f79535-47bb-0310-9956-ffa450edef68