[Development] SIC adding ref-qualified overloads

[Thiago Macieira]

Re: https://codereview.qt-project.org/90981
https://codereview.qt-project.org/90982
https://codereview.qt-project.org/90986
https://codereview.qt-project.org/75296 (5.3)
https://codereview.qt-project.org/74636 (5.3)
https://codereview.qt-project.org/67728 (5.3)

The commits above replace certain const member functions in QString, 
QByteArray and QImage with a pair of ref-qualified member functions (a const & 
and an &&) so that in-place conversion can be performed if possible.

Those changes are technically source-incompatible: if you take the address of 
one of those functions, your code will stop compiling. This was found in 
Creator:
https://codereview.qt-project.org/90988

The change is transparent for regular calls of those functions.

Given the benefits awarded by those changes and the fringe uses of taking PMFs 
to those functions, I'm going to ask that we keep accepting this type of 
changes, with a proper entry in the changelog.

[There's no need to reply if you agree with this proposal]
-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center