ScannerPlugin: Load only relevant files
ScannerPlugin: Load only relevant files

Fixes the following warnings:
WARNING: pluginmanager: couldn't load 'D:\Projects\qt-creator\qbs\plugins\qbs_cpp_scanner.exp'.
WARNING: pluginmanager: couldn't load 'D:\Projects\qt-creator\qbs\plugins\qbs_cpp_scanner.lib'.
WARNING: pluginmanager: couldn't load 'D:\Projects\qt-creator\qbs\plugins\qbs_qt_scanner.exp'.
WARNING: pluginmanager: couldn't load 'D:\Projects\qt-creator\qbs\plugins\qbs_qt_scanner.lib'.

Change-Id: I7e144a389992ba22fed91b0428871577ed903112
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@digia.com>

villytiger/qbs,gatzka/qt-labs-qbs,Distrotech/qbs,qt-labs/qbs,qt-labs/qbs,villytiger/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,Distrotech/qbs,villytiger/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,Distrotech/qbs,villytiger/qbs,qtproject/qt-labs-qbs,Distrotech/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,villytiger/qbs,qt-labs/qbs,gatzka/qt-labs-qbs,Distrotech/qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,Distrotech/qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs