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_boolean_util.c

@@ -485,7 +485,7 @@ static DerivedMesh *ConvertCSGDescriptorsToDerivedMesh(
 	DM_ensure_tessface(result);
 #endif
 
-	CDDM_calc_normals(result);
+	result->dirty |= DM_DIRTY_NORMALS;
 
 	return result;
 }