Reduce buffer size used for parsing config files. There no reason to waste 
100kb of memory -- 16kb is enough to avoid I/O overhead.

Approved by: rhuijben

* subversion/libsvn_subr/config_file.c
  (parse_context_t): Use SVN__STREAM_CHUNK_SIZE (16kb) instead of 
   deprecated SVN_STREAM_CHUNK_SIZE (100kb) for PARSER_BUFFER member.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1581296 13f79535-47bb-0310-9956-ffa450edef68