[Releasing] unforking qtsdk.git

[Oswald Buddenhagen]

hi,

to my astonishment i found that qtsdk actually contains forked copies
of scripts from qt5.git. this is poor engineering practice -
init-repository is *already* diverging for no good reason, and
maintaining both qt.pro and qtsdk.pro will be a pain in the longer run.
therefore i _strongly_ suggest to add an -sdk mode to
qt5/init-repository and delete the qtsdk repository.

the remaining problem is maintaining the submodule sha1s, which may
diverge between qt5 and qtsdk. i guess the easiest way to achieve this
would be adding an sdk-master branch to qt5. it would automatically
merge master after each change (or before the next build), but
specifically ignore the submodule references. that would make master
authoritative for everything but the submodule sha1s, which is what we
want, i think.