It was only needed with Swig versions older than what we have now.

* src/misc/common.hh: Here.
* src/misc/bitvect.hh, src/misc/common.hh, src/ta/taexplicit.hh,
src/ta/taproduct.hh, src/tl/simplify.hh, src/twa/bdddict.hh,
src/twa/taatgba.hh, src/twa/twaproduct.hh: Use = delete directly.