qt: .gitignore generated files

Signed-off-by: Steve Lhomme <robux4@ycbcr.xyz>

modules/gui/qt/dialogs/.gitignore

+extended/ui_equalizer.h
+extended/ui_video_effects.h
+fingerprint/ui_fingerprintdialog.h
+help/ui_about.h
+help/ui_update.h
+open/ui_open.h
+open/ui_open_capture.h
+open/ui_open_disk.h
+open/ui_open_file.h
+open/ui_open_net.h
+podcast/ui_podcast_configuration.h
+messages/ui_messages_panel.h
+preferences/ui_sprefs_audio.h
+preferences/ui_sprefs_input.h
+preferences/ui_sprefs_interface.h
+preferences/ui_sprefs_subtitles.h
+preferences/ui_sprefs_video.h
+sout/ui_profiles.h
+sout/ui_sout.h
+vlm/ui_vlm.h