Remove QTestLog constructor/destructor definitions

Remove QTestLog constructor/destructor definitions

QTestLog is an entirely static class and its constructor and destructor
are declared private to prevent accidental construction of an instance
of the class.  Therefore, the constructor and destructor do not need to
be defined.

Change-Id: I860f1344c5032091f5c641a20e1656bb52a6f07e
Reviewed-on: http://codereview.qt.nokia.com/3466
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>