Debugger: Don't mention auto-detected binaries

... if they are not working properly. E.g. the
pre-build LLDB 3.8 .deb crashes when executing
lldb -version > /dev/null

Change-Id: Ifd468048ffa0d30aeb99283cb64556609d8b1ef6
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/debuggeritemmanager.cpp

@@ -267,6 +267,8 @@ void DebuggerItemManager::autoDetectGdbOrLldbDebuggers()
         item.createId();
         item.setCommand(command);
         item.reinitializeFromFile();
+        if (item.engineType() == NoEngineType)
+            continue;
         //: %1: Debugger engine type (GDB, LLDB, CDB...), %2: Path
         item.setUnexpandedDisplayName(tr("System %1 at %2")
             .arg(item.engineTypeName()).arg(command.toUserOutput()));