Re-add mutex that was taken away in
authorCarl Hetherington <cth@carlh.net>
Wed, 4 Nov 2020 22:33:10 +0000 (23:33 +0100)
committerCarl Hetherington <cth@carlh.net>
Wed, 4 Nov 2020 22:36:56 +0000 (23:36 +0100)
commit0fc3ee1eac41d391ebb79044b0f46849a90f5138
tree4dd05b5aff4a6297adfe9cbc91848c789708db31
parent4b91800c7de893ec1bbc5a00ab245fd6c01b8b25
Re-add mutex that was taken away in
73ebb92e9df01ba7afb97121b6e2cef6ca13a18e

I'm not sure why it was removed, and it seems necessary;
servers_list_changed() can be called from a variety of different places
(the constructor and two different EncodeServerFinder threads).

May help with #1854.
src/lib/j2k_encoder.cc
src/lib/j2k_encoder.h