Passing by value is a potential performance issue, for const comparision (Coverity defect)

include/internal/catch_test_case_registry_impl.hpp

@@ -22,7 +22,7 @@
 namespace Catch {
 
     struct LexSort {
-        bool operator() (TestCase i,TestCase j) const { return (i<j);}
+        bool operator() (const TestCase& i,const TestCase& j) const { return i<j;}
     };
     struct RandomNumberGenerator {
         int operator()( int n ) const { return std::rand() % n; }