Simplify and optimize membuffer cache.
Simplify and optimize membuffer cache.

* subversion/libsvn_subr/cache-membuffer.c
  (svn_cache__membuffer_cache_create): Use apr_pcalloc() for allocate and 
   initialize 'directory' and 'group_initialized' objects. Do not initialize
   'initialize_group' twice.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1125162 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion