modifier stack: lazy initialize normals

many modifiers were calculating normals, when those normals were ignored by the next modifier.
now flag normals as dirty and recalculate for modifiers that set use `dependsOnNormals()` callback.

Quick test on mesh with 12 modifiers (mostly build type), calculated normals 6 times, now it only runs once - so this will give some speedup too.

source/blender/modifiers/intern/MOD_edgesplit.c

@@ -136,7 +136,7 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *ob, DerivedMesh *der
 	result = edgesplitModifier_do(emd, ob, derivedData);
 
 	if (result != derivedData)
-		CDDM_calc_normals(result);
+		result->dirty |= DM_DIRTY_NORMALS;
 
 	return result;
 }