Cleanup: enable Clang-Tidy `bugprone-parent-virtual-call` rule

I added a single `NOLINT` exception with explanation.

No functional changes.

.clang-tidy

@@ -31,7 +31,6 @@ Checks:  >
   -bugprone-sizeof-expression,
   -bugprone-integer-division,
   -bugprone-incorrect-roundings,
-  -bugprone-parent-virtual-call,
   -bugprone-copy-constructor-init,
 
 WarningsAsErrors: '*'

source/blender/freestyle/intern/scene_graph/OrientedLineRep.cpp

@@ -27,7 +27,9 @@ namespace Freestyle {
 
 void OrientedLineRep::accept(SceneVisitor &v)
 {
-  Rep::accept(v);
+  Rep::accept(v);  // NOLINT(bugprone-parent-virtual-call), this seems to intentionally *not* call
+                   // the parent class' accept() function, but rather the grandparent's. The
+                   // v.visitLineRep(*this); call below is actually what the parent class would do.
   if (!frs_material()) {
     v.visitOrientedLineRep(*this);
   }