vim-patch:7.4.364

Problem:    When the viminfo file can't be renamed there is no error message.
            (Vladimir Berezhnoy)
Solution:   Check for the rename to fail.

https://code.google.com/p/vim/source/detail?r=v7-4-364
Merge pull request #1188 from Shougo/vim-patch-7.4.364

vim-patch:7.4.364