Squish: Use lldb for Qt4 desktop kits on Mac

Change-Id: I47874e3ea2b0b2811c66cc0b8866760fdd09755a
Reviewed-by: Robert Loehning <robert.loehning@digia.com>
Squish: Remove special handling for gdb issues on Mac

Change-Id: Ib3473b9f5e984441b7d1dcfe4f5c007e5b435f5a
Reviewed-by: Robert Loehning <robert.loehning@digia.com>