[C PATCH] Backport a fix for PR62294 to 4.9

[Joseph S. Myers]

On Tue, 2 Sep 2014, Marek Polacek wrote:

> PR62294 reports that 4.9 does not emit an "incompatible pointer type"
> warning in certain scenario.  I unknowingly broke this in r207335, and
> then fixed it in r210980, which is a follow-up to the former.  But 4.9
> doesn't have the latter.  This patch is basically a backport of r210980,
> only without the traditional conversion stuff.
> 
> Bootstrapped/regtested on x86_64-linux, ok for 4.9?

OK with a testcase specifically for the regression case added on trunk and 
4.9 if there isn't one already.

-- 
Joseph S. Myers
joseph@codesourcery.com