Use a conditional to avoid accesses the compiler flags as possibly ou…

…t of bounds.

Co-authored-by: Daniel Arndt <arndtd@ornl.gov>

include/deal.II/grid/reference_cell.h

@@ -2195,11 +2195,11 @@ ReferenceCell::contains_point(const Point<dim> &p, const double tolerance) const
   else if (*this == ReferenceCells::Pyramid)
     {
       // A pyramid only lives in the upper half-space:
-      if (p[2] < -tolerance)
+      if (p[dim < 3 ? 0 : 2] < -tolerance)
         return false;
 
       // It also only lives in the space below z=1:
-      if (p[2] > 1 + tolerance)
+      if (p[dim < 3 ? 0 : 2] > 1 + tolerance)
         return false;
 
       // Within what's left of the space, a pyramid is a cone that tapers