Export private symbols for use from other Qt modules

Change-Id: I74aa76cb485cb652eba04ff2387165bab9663c99
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Merge remote-tracking branch 'origin/5.4.0' into 5.4

Change-Id: I62ad6176f085d17152387d2a2ed83a7d9744d4a6