Trivial move of a variable in a smaller “ifndef” scope

tests/jid.cpp

@@ -21,8 +21,8 @@ TEST_CASE("jidprep")
 {
   // Jidprep
   const std::string badjid("~zigougou™@EpiK-7D9D1FDE.poez.io/Boujour/coucou/slt™");
-  const std::string correctjid = jidprep(badjid);
 #ifdef LIBIDN_FOUND
+  const std::string correctjid = jidprep(badjid);
   CHECK(correctjid == "~zigougoutm@epik-7d9d1fde.poez.io/Boujour/coucou/sltTM");
   // Check that the cache does not break things when we prep the same string
   // multiple times