Reduce the processing time of svn log file:///<RUBY>/trunk/ChangeLog on
Windows (repository on SSD) with +- 4% by using an optimized atol()
that doesn't use locale specific parsing when parsing fsfs ids.

Before this patch atol() was by far the most expensive function directly
after the low level file open and read functions. (4.2%->0.33%)

* subversion/include/private/svn_string_private.h
  (svn__strol): New function.

* subversion/libsvn_fs_fs/id.c
  (part_parse,
   txn_id_parse,
   svn_fs_fs__id_parse): Update caller.

* subversion/libsvn_subr/string.c
  (svn__strtol): New function around svn__strtoul.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1605123 13f79535-47bb-0310-9956-ffa450edef68