Silence unused parameter warning in skyline_lu constructor
Silence unused parameter warning in skyline_lu constructor

refs #12

ddemidov/amgcl,huahbo/amgcl,dondieselkopf/amgcl,ddemidov/amgcl,huahbo/amgcl,dondieselkopf/amgcl,ddemidov/amgcl,dondieselkopf/amgcl,ddemidov/amgcl,huahbo/amgcl