Fixed new seemingly random segfaults, by moving the initialization of

Fixed new seemingly random segfaults, by moving the initialization of
delstr from initgc() into collect().  initgc() isn't called unless the
user explicitly imports gc, so can be used only for initialization of
user-visible module features; delstr needs to be initialized for proper
internal operation, whether or not gc is explicitly imported.

Bugfix candidate?  I don't know whether the new bug was backported to
2.2 already.