Follow-up to r1652457: Fix Windows build.
Follow-up to r1652457: Fix Windows build.

* subversion/libsvn_fs_x/util.c
  (construct_txn_path): Use sizeof instead of strlen to determine an upper
                        limit to the length of the constant string.

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1652461 13f79535-47bb-0310-9956-ffa450edef68

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