Logging: support %{time} and %{time format} in QT_MESSAGE_PATTERN

[ChangeLog][QtCore][Logging] QT_MESSAGE_PATTERN can include a
timestamp using %{time} or %{time format}

Change-Id: I2aaa9c7a6fcb340b5ce9f1fe8a78002e5fc4e6fe
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>