Tests: adjusted TODO in grpc_ssl.t, fix committed.

See 23e407a72fe9 for details.
diff --git a/grpc_ssl.t b/grpc_ssl.t
index 5ffa814..06b1cf7 100644
--- a/grpc_ssl.t
+++ b/grpc_ssl.t
@@ -206,7 +206,7 @@
 ok($c = $frame->{headers}{'x-connection'}, 'keepalive - connection');
 
 TODO: {
-local $TODO = 'not yet' if $^O eq 'MSWin32';
+local $TODO = 'not yet' if $^O eq 'MSWin32' and !$t->has_version('1.15.4');
 
 $f->{http_start}('/KeepAlive');
 $f->{data}('Hello');