fixed errors of headercheck for decoupled models while the models/tests still compile!

dumux/decoupled/2p/diffusion/fv/fvpressure2p.hh

dumux/decoupled/2p/diffusion/fv/fvvelocity2p.hh

dumux/decoupled/2p/diffusion/fvmpfa/fvmpfaopressure2p.hh

...oupled/2p/diffusion/fvmpfa/fvmpfaopressureproperties2p.hh

dumux/decoupled/2p/diffusion/mimetic/mimeticgroundwater.hh

dumux/decoupled/2p/diffusion/mimetic/mimeticpressure2p.hh

...upled/2p/diffusion/mimetic/mimeticpressureproperties2p.hh

dumux/decoupled/2p/impes/gridadaptionindicator2p.hh

dumux/decoupled/2p/impes/impesproperties2padaptive.hh

dumux/decoupled/2p/transport/fv/capillarydiffusion.hh

dumux/decoupled/2p/transport/fv/diffusivepart.hh

dumux/decoupled/2p/transport/fv/fvsaturation2p.hh

dumux/decoupled/2p/transport/fv/fvtransportproperties2p.hh

dumux/decoupled/2p/transport/transportproblem2p.hh

dumux/decoupled/2p/transport/transportproperties2p.hh

dumux/decoupled/2p/variableclass2p_gridadapt_old.hh

dumux/decoupled/2p/variableclass2p_old.hh

dumux/decoupled/common/decoupledproperties.hh

dumux/decoupled/common/fv/fvpressure.hh

dumux/decoupled/common/fv/velocitydefault.hh