fix loop logic cruft in dynamic tls installation

fix loop logic cruft in dynamic tls installation

commit 9d44b6460ab603487dab4d916342d9ba4467e6b9 inadvertently
contained leftover logic from a previous approach to the fallback
signaling loop. it had no adverse effect, since j was always nonzero
if the loop body was reachable, but it makes no sense to be there with
the current approach to avoid signaling self.