1.45_01: C: dynamic COP file and stash threaded

tagged Feb 12, 2014 · 897 commits to master since this tag

several core tests (not one of our so far) do a cv_undef, which clears
the CvROOT op, which is a COP. So all COP fields must be dynamic, even under threads.

tested with t/CORE/op/bproto.t