On the fsfs-format7 branch: Make extracting string data from our containers
much more efficient.  The key is that we stitch them together from very
small fragments (often < 10 chars) but can allocate buffers in a way that
allows us to do "sloppy" copying.

* subversion/libsvn_fs_fs/string_table.c
  (PADDING): define new constant
  (add_table,
   create_table): ensure that the string data buffer has 8 extra bytes
  (copy_masks): new useful lookup table
  (table_copy_string): use a "sloppy" but much faster copying scheme
  (svn_fs_fs__string_table_get,
   svn_fs_fs__string_table_get_func): ensure that the target buffer has
                                      the necessary extra padding, too


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1485910 13f79535-47bb-0310-9956-ffa450edef68