Match: Check for onlyname Only Once

instead of checking every run around the loop.

Looking at spesh made me realize that every
time it goes through the loop it also tried to
sink the result of the if.

src/core/Match.pm6

@@ -45,14 +45,14 @@ my class Match is Capture is Cool does NQPMatchRole {
                         $namecount = nqp::add_i($namecount, 1);
                         if nqp::iterval(nqp::shift($iter)) >= 2 {
                             $name = nqp::iterkey_s($iter);
-                            $onlyname = $name if nqp::iseq_i($namecount, 1);
                             nqp::iscclass(nqp::const::CCLASS_NUMERIC, $name, 0)
                                 ?? nqp::bindpos(
                                         nqp::if(nqp::isconcrete($list), $list, ($list := nqp::list())),
                                         nqp::fromstr_I($name, Int), [])
                                 !! nqp::bindkey($hash, $name, []);
                         }
                     }
+                    $onlyname = $name if nqp::iseq_i($namecount, 1);
                 }
             }