Added build-werror config to error on build warnings

Summary: Adding this build to TeamCity will give us a way to track when VLA and thread-safety-analysis issues show up.

Test Plan:

git checkout master
ABC_BUILD_NAME=build-werror ./build-configurations.sh  # passes

git checkout ebf7876  # Commit on master with thread-safety-analysis warnings
ABC_BUILD_NAME=build-werror ./build-configurations.sh  # fails

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D4287