[CTest] fixed skipping tests if AluGrid is not found.

reviewed by gruenich
wq


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15027 2fb0f335-1f38-0410-981e-8018bf24f1b0

test/decoupled/2p/test_3d2p.cc

@@ -184,7 +184,7 @@ int main(int argc, char** argv)
 int main()
 {
     std::cerr << "You need to have ALUGrid installed to run this test\n";
-    return 1;
+    return 77;
 }
 
 #endif