Updated comments in spell.h/.c to follow the style guide.
vim-patch:7.4.269

Problem:  CTRL-U in Insert mode does not work after using a cursor key.
          (Pine Wu)
Solution: Use the original insert start position. (Christian Brabandt)

https://code.google.com/p/vim/source/detail?r=81c26975e8f9dc7435353581346542409403f296