Generate includes for Qt containers used as auto-metatypes.

Generate includes for Qt containers used as auto-metatypes.

Otherwise the containers might be forward declared in the moc file,
and when the moc file is compiled in a standalone translation unit,
the full definition of it would not be available. This results in
odd compile errors, so instead generate the includes if required.

Change-Id: Ie01c5a5d45314daad0b00dec03b3e1e18cdbae64
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Volker Krause <volker.krause@kdab.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>