New function are not public

According to https://github.com/couchbase/libcouchbase/releases/tag/2.7.6

• `lcb_resp_get_error_context(int, const lcb_RESPBASE *)`
• `lcb_resp_get_error_ref(int, const lcb_RESPBASE *)`
  But this functions don't have the LIBCOUCHBASE_API attribut, so are not visible

See abi-compliance-checker report: https://git.remirepo.net/cgit/rpms/lib/libcouchbase.git/plain/compat_reports/2.7.5_to_2.7.6/compat_report.html?id=0c1d0c9c23dd36546394440b8f3215af261e6fea

  (visible in "Sources" as "Added symbols", but missing in "Binary")