GCC10: warning: catching polymorphic type 'struct dmlc::Error' by value

[ggardet]

With GCC10, there is the following warning:

[ 1395s] /home/abuild/rpmbuild/BUILD/incubator-tvm-0.7.0/tests/cpp/ir_functor_test.cc: In member function 'virtual void IRF_ExprTransform_Test::TestBody()':
[ 1395s] /home/abuild/rpmbuild/BUILD/incubator-tvm-0.7.0/tests/cpp/ir_functor_test.cc:75:18: warning: catching polymorphic type 'struct dmlc::Error' by value [-Wcatch-value=]
[ 1395s]    75 |   } catch (dmlc::Error) {
[ 1395s]       |                  ^~~~~

Something like } catch (dmlc::Error&) { should fix it.

[tqchen]

thanks @ggardet can you send a new PR ?