Fix qtscript build for WEC7 by bringing ce-compat back to Qt5 .

JSCore build for WEC7 depends on ce-compat, and apparently it was
vanished as a part of Qt modularization or some other cleanup.

Copied relevant files and pro file lines form Qt4 back to QtScript repo
under 3rdparty folder.

Change-Id: Ic710be105df17b44962553ae3b61401b2dd6fab5
Reviewed-by: Björn Breitmeyer <bjoern.breitmeyer@kdab.com>
Reviewed-by: Johannes Oikarinen <johannes.oikarinen@digia.com>
Reviewed-by: Andreas Holzammer <andreas.holzammer@kdab.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>