Use mutex locking instead of pseudo-locking the weak pointer in the search API.
Use mutex locking instead of pseudo-locking the weak pointer in the search API.

thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS