untracked threadIds have been observed and can result in crashes.
s_getCurrent() already checks them and s_setCurrent() does it now.
(cherry picked from commit bf8e3135ac906ce0ab7d6d9ccbd434f1597f2ff4)
Conflicts:
cppu/source/uno/EnvStack.cxx
Change-Id: If35237179c1ee3b854e6183294ed72a6d0b105a8