Remove obsolete QMetaObject::activate() overloads.

Remove obsolete QMetaObject::activate() overloads.

The overloads taking a range were previously used for cloned signals
(ones that had default arguments). Commit
919b723088b8617b202b92d80b8d0983e4fd9500 changed how cloned signals are
handled, making the from,to overloads obsolete.

The 3 argument activate() overload that does not take a QMetaObject
argument was marked obsolete by the same commit, but considering that it
is used by our autotests, I've decided to keep it and not mark it as
obsolete anymore.

Change-Id: I631ce84dce156dec68cf26e10787cb35e3f50e18
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>