Remove declaration-after-statement C warning

[Mark Kettenis]

> From: Bart Massey <bart at cs.pdx.edu>
> Date: Wed, 11 Sep 2013 23:49:06 -0700
> 
> I'm talking about a programming convention that is supported by the
> existing C language, has no associated cost, complexity or difficulty,
> does not make significant semantic or syntactic change to programs, is
> easy to learn, and yet helps to prevent a common kind of bug.

But there is an associated cost.  With the C90 rules, I know where to
look for local variable declarations; they're right at the start of a
block (hopefully) seperated by a blank line from the actual code.  So
I waste less time reading the code.