ProjectExplorer: Simplify BuildStepFactory

De-QObject-ify class, tr contexts are now the product's
context, which was the case in some BuildStepFactories already,
and is current state in {Run,DeployConfiguration}Factory.
One spurious object name removed.

De-virtualize canHandle(), it was never overloaded and is not
intended to be overloaded anymore.

Remove unused clone() function.

Change-Id: Iff7fba5f707505f868f94458084a18650535fa23
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/autotoolsprojectmanager/makestep.cpp

@@ -56,7 +56,6 @@ MakeStepFactory::MakeStepFactory()
         }
     };
 
-    setObjectName("Autotools::MakeStepFactory");
     registerStep<Step>(MAKE_STEP_ID);
     setDisplayName(ProjectExplorer::MakeStep::defaultDisplayName());
     setSupportedProjectType(AUTOTOOLS_PROJECT_ID);