[RFC] vim-patch:7.4.237

Merging vim-patch:7.4.237
Code update in PR ([neovim/#569](https://github.com/neovim/neovim/pull/569))

Problem:    When some patches was not included has("patch-7.4.123") may return
            true falsely.
Solution:   Check for the specific patch number.

https://code.google.com/p/vim/source/detail?r=71b165a378ad580818f6d497ecf0f8ad054a9683