[PR18457] Don't require rtld lock to compute DTV addr for static TLS

[Carlos O'Donell]

> diff --git a/nptl/tst-join7.c b/nptl/tst-join7.c
> new file mode 100644
> index 0000000..bf6fc76
> --- /dev/null
> +++ b/nptl/tst-join7.c
> @@ -0,0 +1,12 @@
> +#include <dlfcn.h>

I have commented downstream on the patch, but I just wanted to
note that all test cases need FSF header, and a single line
explaining what the test does.

Cheers,
Carlos.