QMake: Fix parsing of WARNINGS
QMake: Fix parsing of WARNINGS

Handle qmake warnings that start with WARNING: or ERROR: but do not
contain any obvious filename.

Task-number: QTCREATORBUG-14335
Change-Id: I5b4cedbb7408c74092fb81412cc50b37e4698b7e
Reviewed-by: Daniel Teske <d8a411aec9a206efedb4d45b75fe8d13f1e2b628@theqtcompany.com>

martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator