Utils: Fix bug in commonPath() with directories
Utils: Fix bug in commonPath() with directories

The algorithm expected a list of filenames, but the cmake plugin passed
in a list containing a directory and a filename. Appending a slash to
each entry. (Except root entries.) fixes this.

Task-number: QTCREATORBUG-13606
Change-Id: I518a2601295017636f4c450cc8a9026f4b41689a
Reviewed-by: Eike Ziller <c142da16c73a95a82d35191bcc55b22835617128@theqtcompany.com>

xianian/qt-creator,kuba1/qtcreator,farseerri/git_code,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,Distrotech/qtcreator,danimo/qt-creator,danimo/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,amyvmiwei/qt-creator,kuba1/qtcreator,AltarBeastiful/qt-creator,danimo/qt-creator,Distrotech/qtcreator,kuba1/qtcreator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,xianian/qt-creator,farseerri/git_code,danimo/qt-creator,amyvmiwei/qt-creator,danimo/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator,Distrotech/qtcreator,AltarBeastiful/qt-creator,xianian/qt-creator,kuba1/qtcreator,amyvmiwei/qt-creator,Distrotech/qtcreator,danimo/qt-creator,Distrotech/qtcreator,xianian/qt-creator,AltarBeastiful/qt-creator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,kuba1/qtcreator,xianian/qt-creator,amyvmiwei/qt-creator,danimo/qt-creator,Distrotech/qtcreator,farseerri/git_code,farseerri/git_code,AltarBeastiful/qt-creator,kuba1/qtcreator,danimo/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,Distrotech/qtcreator,farseerri/git_code,kuba1/qtcreator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,xianian/qt-creator,farseerri/git_code,kuba1/qtcreator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,danimo/qt-creator,kuba1/qtcreator