rem: * per-thread. At thread exit, DeleteInterps will be called * to free any interps remaining on the thread cache.
add: * per-thread. At thread exit, DeleteData will be called * to free any interps remaining on the thread cache * and remove the async cancel handler.
context: NsInitTcl(void){    /*     * Allocate the thread storage slot for the table of interps     * per-thread. At thread exit, DeleteInterps will be called     * to free any interps remaining on the thread cache.     */    Ns_TlsAlloc(&tls, DeleteInterps);    Tcl_InitHashTable(&interps, TCL_STRING_KEYS);    Ns_MutexSetName(&ilock, "ns:interps");}