Adds --with-cpack option.
- macOS: does nothing (we already create a better, signed disk image)
- Linux: creates qtcreator.deb in build directory
- Windows: Checks for NSIS and WIX installation,
creates qtcreator.exe and qtcreator.msi as appropriate
Change-Id: Ie7816d04cb2e01e90795481e1519b0a6645f5cd3
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
c72a9197a4