Simplify the hash function used for the DAG node cache.
Simplify the hash function used for the DAG node cache.

* subversion/libsvn_fs_fs/tree.c
  (cache_entry_t): peg hash_value to unsigned 32 bits which minimizes
                   the number of casts we have to do
  (cache_lookup): same here, including FACTOR;
                  drop the chunky alternative to unaligned data access

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1495805 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion