devel/alabastra: unbreak with clang 4.0

src/AlWinMain.cpp:164:35: error: ordered comparison between pointer and zero ('QListWidgetItem *' and 'int')

if (ui.list_files->currentItem() > 0)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~

src/AlWinMain.cpp:722:16: error: ordered comparison between pointer and zero ('AlTextEdit *' and 'int')

if (actualTxt > 0 && ui.list_files->currentItem() > 0)
    ~~~~~~~~~ ^ ~

src/AlWinMain.cpp:722:52: error: ordered comparison between pointer and zero ('QListWidgetItem *' and 'int')

if (actualTxt > 0 && ui.list_files->currentItem() > 0)
                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~

src/AlWinMain.cpp:731:16: error: ordered comparison between pointer and zero ('AlTextEdit *' and 'int')

if (actualTxt > 0 && ui.list_files->currentItem() > 0)
    ~~~~~~~~~ ^ ~

src/AlWinMain.cpp:731:52: error: ordered comparison between pointer and zero ('QListWidgetItem *' and 'int')

if (actualTxt > 0 && ui.list_files->currentItem() > 0)
                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~

Reported by: antoine (via exp-run)