library: recycle the QUICK_THREADS #define, <PIDS> api

library: recycle the QUICK_THREADS #define, <PIDS> api

That #define QUICK_THREADS was impossible to implement
under the new <pids> interface. Plus it was also found
to distort some thread information (referenced below).

So, it's always been inactive under the newlib branch.

However, it will (with small changes) still serve some
useful purpose in our library. Now, when the redefined
FALSE_THREADS is active, those special strings showing
"[ duplicate ENUM ]" will appear for any child thread.

Note: the real reason for such strings appearing isn't
being exercised, only their mechanics. In actual usage
they are substituted when a user duplicates such items
in a results stack & only the 1st instance can own it.

With this patch, we are simply fooling the <pids> code
into thinking an item was duplicated via a NULL value.

Reference(s):
. from master branch
commit 25a6ecdbfb3262261465ce1dd0e0e758cf3ac497

Signed-off-by: Jim Warner <james.warner@comcast.net>