Failing build when linking with OpenSSL

[ben-crowhurst]

$ make
Linking CXX shared library librestbed.dylib
Undefined symbols for architecture x86_64:
"_ERR_remove_thread_state", referenced from:
asio::ssl::detail::openssl_init_base::do_init::~do_init() in service.cpp.o
asio::ssl::detail::openssl_init_base::do_init::~do_init() in service_impl.cpp.o
asio::ssl::detail::openssl_init_base::do_init::~do_init() in session.cpp.o
asio::ssl::detail::openssl_init_base::do_init::~do_init() in session_impl.cpp.o
asio::ssl::detail::openssl_init_base::do_init::~do_init() in socket_impl.cpp.o
"_TLSv1_1_client_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
"_TLSv1_1_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
"_TLSv1_1_server_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
"_TLSv1_2_client_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
"_TLSv1_2_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
"_TLSv1_2_server_method", referenced from:
asio::ssl::context::context(asio::ssl::context_base::method) in service_impl.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [librestbed.dylib] Error 1
make[1]: *** [CMakeFiles/restbed.dir/all] Error 2
make: *** [all] Error 2

[ben-crowhurst]

This issue happens when one or more versions of OpenSSL have been installed on a system and the headers being used don't make the library found.

To resolve this issue remove duplicate installations of OpenSSL and/or fix search paths.