Within FSFS, replace the use of svn__strtol with a variant that
provides overflow detection.  FSFS needs a locale-independent
and preferrably quick number parser.

This is to eventually get rid of svn__strtol.

* subversion/libsvn_fs_fs/id.c
  (fast__strtol): New local function, mainly taken form string.c
                  but with overflow checks and state return added.
  (part_parse,
   txn_id_parse,
   svn_fs_fs__id_parse): Update callers.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1618641 13f79535-47bb-0310-9956-ffa450edef68