[Toybox] [CLEANUP] ifconfig commit 862

[Rob Landley]

Filling out the cleanup.html page, there are some commits I didn't post 
  message explaining. So I'm backfilling a bit as I fill in the web page.

Commit http://landley.net/hg/toybox/rev/862

The usual whitespace collation and inlining. Remove more unused headers. 
Remove function setport() which is never called.

In get_ifconfig_info(), replace char buff[BUFFSZ] with toybuf. (We have 
to track what's using toybuf, but as long as the uses don't overlap 
we're good.)

The get_device_info() return failure can just perror_exit(), no need for 
cleanup and calling strerror() ourselves. Again, remove as much english 
text from the error messages as possible so we don't have to translate 
it, rely on the translated strerror() text to explain the problem.

Also, no need to set a local variable to NULL on the way out of the 
function, nothing else can use it after that point.