Don't try/catch with --disable-exceptions

I need to get CI to start using -fno-exceptions for that case...

Author: roystgnr

tests/mesh/mesh_input.C

@@ -919,8 +919,10 @@ public:
       // Debugging this in parallel is tricky.  Let's make sure that
       // if we have a failure on one rank we see it on all the others
       // and we can go on to other tests.
+#ifdef LIBMESH_ENABLE_EXCEPTIONS
       bool threw_exception = false;
       try
+#endif // LIBMESH_ENABLE_EXCEPTIONS
       {
       for (const auto & elem : mesh.active_local_element_ptr_range())
         {
@@ -987,6 +989,7 @@ public:
             }
         }
       }
+#ifdef LIBMESH_ENABLE_EXCEPTIONS
       catch (...)
       {
         threw_exception = true;
@@ -996,6 +999,7 @@ public:
       if (!threw_exception)
         TestCommWorld->max(threw_exception);
       CPPUNIT_ASSERT(!threw_exception);
+#endif // LIBMESH_ENABLE_EXCEPTIONS
 
       TestCommWorld->sum(n_side_nodes);
       CPPUNIT_ASSERT_EQUAL(n_side_nodes, n_fake_nodes);