[Development] GCC-built Qt 5.6 can't be used with Clang

[Welbourne Edward]

> Simon Hausmann wrote:
>> Hmm, change ‎https://codereview.qt-project.org/#/c/147846/ was
>> supposed to fix this issue.
>>
>> ‎The subject of the email refers to 5.6 but in the body you say that
>> you are building the dev branch. If it is the latter, could it be
>> that the fix hasn't hit dev yet?

Stephen Kelly replied
> Indeed, I built without that patch. Perhaps it is indeed fixed in 5.6
> already (but I didn't check). Reading the commit message and the
> commit I don't have the expertise to know.

It was commit 3726c46735edb23ad37af818ff7d52d661ec87e7.
I'm sure there's a specific command for asking git whether a given
branch contains a given commit: but I can't remember it.
Still, git log dev..3726c4673 reveals that it is indeed not yet in dev.
(Or, at least, wasn't this morning when my nightly cron job pulled into
my local bare repos.)

	Eddy.