Following up on r1427210, document some of the unaligned access magic by using similar pointer calculations in more cases. Document the + 1's in the pointer calculations.
Following up on r1427210, document some of the unaligned access magic by using
similar pointer calculations in more cases. Document the + 1's in the pointer
calculations.

* subversion/libsvn_diff/diff_file.c
  (find_identical_suffix): Make the can_read code easier to follow; add some
     comments. Reduce scope of single-use variable.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1427237 13f79535-47bb-0310-9956-ffa450edef68

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