[RFC] Transform global variable really_exiting into static.

Transform global variable really_exiting into static and some minor style changes.

Comments are welcome.
I'm with a little trouble understanding what you're trying to say. This is my interpretation (Figure below):

Comment (1) ~ starting
Comment (2) ~ exiting
Comment (3) ~ really_exiting
Comment (4) ~ full_screen
Comment (5) ~ full_screen

So I moved comment (3) within really_exiting declaration.

Could you please tell how to fix it? (e.g., move comment (x) to y)

Sorry to bother you with this possible misunderstanding.
![nvim_really_exiting](https://cloud.githubusercontent.com/assets/800493/5550632/810fc402-8b91-11e4-90c6-f0bda66a476f.png)