On svn_mutex branch: Switch  BDB environment management the safer svn_mutex__t. Simplify locking-related code when possible.
On svn_mutex branch:
Switch  BDB environment management the safer svn_mutex__t.
Simplify locking-related code when possible.

* subversion/libsvn_fs_base/bdb/env.c 
  (bdb_cache_lock): we can always have the - maybe dummy -  mutex objects
  (clear_cache): svn_mutex__t* will be cleaned up automatically
  (bdb_init_cb): simplify using new API
  (acquire_cache_mutex, release_cache_mutex): drop
  (svn_fs_bdb__close): move syn'ed part to svn_fs_bdb__close_internal
  (svn_fs_bdb__open): move syn'ed part to svn_fs_bdb__open_internal


git-svn-id: 381aa894c3e6af1db0f31a0b5460797f4bbc1b6a@1145331 13f79535-47bb-0310-9956-ffa450edef68

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