[TCLCORE] PURIFY and unloading extensions issue (?)

[Neophytos D. <neo...@gm...>]

Hi,

When the PURIFY flag is used Tcl_Exit calls Tcl_Finalize that in turn calls
TclFinalizeSynchronization, which sets tsdGlobal.key to NULL via
TclFinalizeThreadStorage.

Then, when it afterwards tries to unload extensions, it attempts to use the
TSD (thread-specific data) again and because tsdGlobal.key is NULL, the
AddressSanitizer complains about a NULL pthread key.

I was not able to track where the TSD is used during unloading or if this
is an issue with the extensions being used and whether they have to unload
in a specific way. As a consequence I stopped using the PURIFY flag but if
anyone has any suggestions, please let us know.

Kind regards,
Neophytos