Fix glue symbol mangling

[brson]

Here's an example of what we're looking at:

unstablesyncUnsafeAtomicRcBoxunstableatomicsAtomicOptionrtcommChanOnertcommStreamPayload_of_::_1889f9c1bacda27d::glue_drop_53969

Needs more colons.

[brson]

Actually colons plus some substitute for < >. Just make it readable.