fix definition of surfaces and volume

benchmarks/extrude/aorta_extrude.geo

@@ -9,14 +9,13 @@ out1[] = Extrude{Surface{-1}; Layers{4, 0.5}; Using Index[0]; Using View[0]; };
 // we could create a second boundary layer inside...
 //out2[] = Extrude{Surface{1}; Layers{4, -0.5}; Using Index[1]; Using View[0]; };
 
-Line Loop(60) = {9}; Plane Surface(61) = {60};
-Line Loop(62) = {7}; Plane Surface(63) = {62};
-Line Loop(64) = {10}; Plane Surface(65) = {64};
-Line Loop(66) = {11}; Plane Surface(67) = {66};
-Line Loop(68) = {8}; Plane Surface(69) = {68};
+Line Loop(60) = {1}; Plane Surface(61) = {60};
+Line Loop(62) = {2}; Plane Surface(63) = {62};
+Line Loop(64) = {3}; Plane Surface(65) = {64};
+Line Loop(66) = {4}; Plane Surface(67) = {66};
+Line Loop(68) = {5}; Plane Surface(69) = {68};
 
 Mesh.Algorithm3D = 4;
 
-Surface Loop(100) = {32, 61:69:2};
+Surface Loop(100) = {1, 61:69:2};
 Volume(100) = 100;
-