make qt_module_config.prf install the module pri file

make qt_module_config.prf install the module pri file

absorb module.prf into qt_installs.prf, as that's where it belongs.
add qt_install_module option and automatically set it in
qt_module_config. make qt_installs use that option.

Change-Id: I860616f3a29a456f7b88ddaffa09375400c8911e
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>