Build fails on macOS 10.12 (Sierra) with LLVM Clang 8.0.0 in src/lib/asiolink/simple_callback.h:66:64

[cstrotm]

Making all in .
  CXX      libbundy_asiodns_la-dns_service.lo
In file included from dns_service.cc:19:
In file included from ./dns_service.h:21:
../../../src/lib/asiolink/simple_callback.h:66:64: error: all paths through this function will call itself [-Werror,-Winfinite-recursion]
    virtual void operator()(const IOMessage& io_message) const {
                                                               ^
In file included from dns_service.cc:24:
In file included from ./tcp_server.h:27:
./dns_server.h:77:5: error: all paths through this function will call itself [-Werror,-Winfinite-recursion]
    {
    ^
In file included from dns_service.cc:24:
In file included from ./tcp_server.h:28:
./dns_lookup.h:78:5: error: all paths through this function will call itself [-Werror,-Winfinite-recursion]
    {
    ^
3 errors generated.