patch to not warn about infinite loops

[Jason Merrill]

>>>>> "Geoff" == Geoff Keating <geoffk@geoffk.org> writes:

>> From: Jason Merrill <jason@redhat.com>
>> 
>> Rather than add a new flag, I would think it would make sense to bundle
>> this in with -Wreturn-type.

> The two warnings seem to be different enough that they should have
> different flags.  

I disagree.  -Wreturn-type already warns about functions failing to return
a value.  My new warning was to fill a hole where -Wreturn-type was failing
to warn because we weren't running flow.  If it's going to be
conditionalized on a flag, that should be the one.

Jason