Fix compile warning in icetime.cc

icetime.cc: In function ‘std::__cxx11::string ecnetname_to_vlog(std::__cxx11::string)’:
icetime.cc:1323:32: warning: catching polymorphic type ‘class std::invalid_argument’ by value [-Wcatch-value=]
  } catch(std::invalid_argument e) { // Not numeric and stoi throws exception
1 file changed