[LyX/master] C++11 compilation fix

[Jürgen Spitzmüller]

Am Mittwoch, dem 07.12.2022 um 18:15 +0100 schrieb Jean-Marc
Lasgouttes:
> My comment that it is a C++11 thing is probably wrong. I did not
> check what level of standard allows QPair without specialization.
> This issue was the reason why std::pair has a make_pair(), I think.

I am completely fine with using std::pair, as suggested by Scott, if
this makes things easier.

-- 
Jürgen