CppTools: Do not return a language option for ProjectFile::Unclassified
CppTools: Do not return a language option for ProjectFile::Unclassified

This led to an invalid command line ("-x" without further argument).

Change-Id: I8cfe1a8a29789fba426b61fe3702496d8089db6b
Reviewed-by: Marco Bubke <5254e489b34ec8bbce36789100e3fc0f41fa62ef@theqtcompany.com>

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