Merge remote-tracking branch 'origin/5.5' into 5.6

Conflicts:
	src/network/socket/qnativesocketengine_p.h
	src/network/ssl/qsslsocket_mac.cpp
	src/network/ssl/qsslsocket_mac_p.h
	src/widgets/kernel/qwidget.cpp

Change-Id: I39592cb37d710dfaf8640769ba3c1b637927d7f4