Ignore /dev/null in actool output parser.
Ignore /dev/null in actool output parser.

The null device must be passed to --output-partial-info-plist as part
of output artifact tracking but should not be tracked as an artifact.

Change-Id: I2f63bb23be800eb46e68c46086ee53c42f49e5fc
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@theqtcompany.com>

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