Fix empty variadic arg warning

Author: horenmar

src/catch2/internal/catch_run_context.cpp

@@ -65,7 +65,8 @@ namespace Catch {
                             INTERNAL_CATCH_MSG(
                                 "SKIP",
                                 Catch::ResultWas::ExplicitSkip,
-                                Catch::ResultDisposition::Normal );
+                                Catch::ResultDisposition::Normal,
+                                "" );
                             Catch::Detail::Unreachable();
                         }
                         // '*' is the wildcard for "all elements in generator"