I am getting this error when compiling a clear version of master branch. ``` CC src/common/src_common_libor_crypto_testing_a-crypto.o src/common/compress_zstd.c:63:1: error: ‘tor_zstd_format_version’ defined but not used [-Werror=unused-function] tor_zstd_format_version(char *buf, size_t buflen, unsigned version_number) ^~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors make[1]: *** [Makefile:5893: src/common/src_common_libor_crypto_testing_a-compress_zstd.o] Error 1 ``` The error seems to come from commit [b56fd17d0003b0b66570a7d99aadbe901144f75d](https://gitweb.torproject.org/tor.git/commit/?id=b56fd17d0003b0b66570a7d99aadbe901144f75d). Travis CI report [here](https://travis-ci.org/torproject/tor/builds/342171373?utm_source=github_status&utm_medium=notification).